New issue just popped up. Any further idea's?

For several weeks the wagon has been starting just a little slow.  Not something I worried much about, but now it has gotten worse.

If the sits for 4-5 days (maybe less) it cranks along time before it will start, as much as 45 seconds.  It acts like it is not getting or starving for fuel like maybe it is loosing prime.  Once it starts and runs for a few moments it is normal and starts ok, just a little slow.  I took the cap off the schrader valve on the fuel injection and it is wet inside and of course smells of fuel. I put my gauge on it and it had zero pressure and it had started about 30 minutes previous.  So I ran the pump and it went to 42 psi quickly and when it shut off it held between 38-40 psi.  It runs at idle at 36 psi at idle when I blip the throttle it goes up to approx 42 psi.  

• Fuel pump has very few miles and it is a GM pump.  
  

• No wetness on the lines or smell.
  

Suspects:

• Fuel pump check valve failing
  

• Clear hose in sending unit cracked/split
  

• Schrader valve failing?
  

So I left the pressure gauge on the rail for a couple of hours. It was down to 20-23 PSI. I pulled the injectors and rail out of the intake and put a blue paper town under each. I then pressurized them. No leak yet.

The schrader valve is now out of play as well as it has the gauge on it and still leaking down.

If it is not the injectors leaking down I would think it has to be the pump or hose in the sending unit, I have seen these split before. I will let the pressure leak down over the next hour or so and then see if I have any leaks. Also putting a paper town under the regulator, it is new but just in case.

I know they're not identical, but I had similar problems on a TBI car. It had a broken clamp on the pump discharge hose in the sending unit.

Could be the fuel pressure regulator, too.

Fairly new pressure regulator so I am pretty confident that is not it. The fuel rail did not leak, so I pulled the tank. I hear a hissing inside the pump as is drains on the ground. I have a known good pump in the garage so I will put that in. The sending unit is a spectra unit and again very recent, but I will see if I can get a hose for it and replace that as well. Hope this fixes it.

Fuel pressure regulator.... and I don't care that it's relatively new.

Next time it sits for awhile if it's still leaking down, turn the ignition on until the fuel pump stops, then off. Repeat 5-6 times. Then try to start the car, and it if starts right up, then the leakdown is your problem.

Tim,what was the last thing you worked on/replaced before you began noticing the problem?
START THERE!

The injectors were not leaking down. I pulled the sender and pump out of the tank. All looks good. Advance Auto replaced the regulator, no questions asked (they know me well down there) and put the injectors and rails back in. Got busy re-constructing my heat shields and did not get the tank back in. Rust proofed some of the under carriage while I was under there. I will put the tank back in after church tomorrow morning and re-check how she holds pressure. Only time will tell.

And it fixed nothing. The pressure still drops over time when I let the car sit.

I'd consider it a non-critical problem. Is there a checkvalve INSIDE the fuel pump?

sherlock9c1 wrote:

I'd consider it a non-critical problem.  Is there a checkvalve INSIDE the fuel pump?  

So I inspected my fuel lines yesterday and remebered a slight kink I had on one line.  No leak appearing to happen, but I thought I would remove the bad area anyway.  So I used a compression fitting designed for nylon to nylon line in my buddies (now mine) fuel line repair kit.  I removed about 1" of the line and put the compression fitting in its place (right by the fuel filter).  I then put the test gauge on it and she held 39-40 psi for about 90-120 minutes.  Much better than before.  So we will see how it starts on Thursday.

Was it leaking gas? How did fixing the kink physical affect fuel pressure?

it did not seem to be leaking fuel. But I thought maybe there was a small leak.

Could be the small kink, good read up anyway, going one step at the time. Thnx for sharing

I am thinking that feds upped the "ethanol" level and didnt tell anyone.

Well this week I was up in Syracuse on business. Car ran great but was starting slow all week. Typically would take 2 cranks to get her to fire. On Wednesday it let me sit for 1/2 or so. Finally got her to fire then it ran fine.

Parked it at my hotel and got a ride for a colleague the rest of the week. Let the office Thursday afternoon and got her running. Drove to a friends house and tore into it. The fuel pressure was down to 25-30. NO WONDER IT WOULD NOT START WELL!! New fuel pressure regulator failing!! Not happy. Ordered a new one from AZ and left it apart for the night. Took the time to polish my fuel rails (thanks Mike!!) and clean her up a bit. Got the new regulator in by 10am this morning and she runs great!!

Side note - It is not developing pressure in the tank. The cap does not suck air in when I remove it. It used to always to that. I switched my cap with my Impala tonight to take that off the list. I guess the charcoal canister would be the next thing to look at.

Good tht it's solved. The part of the pressure in the tank, my tank Always sucks air in when i get the gas cap open. (93 TBI) Is that normal?
Pete

Dutch Pete wrote:

Good tht it's solved. The part of the pressure in the tank, my tank Always sucks air in when i get the gas cap open. (93 TBI) Is that normal?
Pete

Most if not all the guys here are passing GAS in one way or another and yes that suction sound you hear is normal with all the TBI wagons!








Sorry guys,I couldnt let that gas comment go!

So today I noticed that the throttle was not fully returning to idle when I let off it slowly. It has been a long time since I cleaned the throttle body. So I took it off and cleaned up up a bit inside and out. When I put it back together the idle went way up and would not come down (1400-2000rpm). So I played with it a bit and I guess I smoked my Throttle Position Sensor with throttle body cleaner. Ooops! I had a spare to now it runs amazingly well. With everything fresh it has more SOTP HP then it ever has! What a blast to drive this old thing!!

Flasheroo wrote:

Dutch Pete wrote:

Good tht it's solved. The part of the pressure in the tank, my tank Always sucks air in when i get the gas cap open. (93 TBI) Is that normal?
Pete

Most if not all the guys here are passing GAS in one way or another and yes that suction sound you hear is normal with all the TBI wagons!

Sorry guys,I couldnt let that gas comment go!

If the system is pulling a vacuum on the tank, than change the cap!  It is designed to let air in not out.  Will allow small amounts of pressure, controlled by the canister valve.  The cap is supposed to prevent vacuum.

Bill

So, I paid a visit to Tim today and helped him pull his tank and we swapped (I think lol!) fuel pumps back to the ACDelco (at least that's what when in!). It seems the check valve on the Spectre was done. We also replaced the o-ring around the pump assembly. This time when he keyed it on, the psi shot up to 46. It stayed there a bit and slowly lowered, but hovered around 40 for the most part.

My question is this: Could the o-ring around the fuel pump assembly have caused these problems? It didn't seem so much as it was "sealing" the pump like with A/C and other o-rings.

By the way, it was great to meet Tim and his family! He has a VERY fine wagon (yes, I gave the "oh $h*t," when my head snapped on the test drive). I went from, "so what made you put a manual in this car?" To this....

convert2diesel wrote:

Flasheroo wrote:

Dutch Pete wrote:

Good tht it's solved. The part of the pressure in the tank, my tank Always sucks air in when i get the gas cap open. (93 TBI) Is that normal?
Pete

Most if not all the guys here are passing GAS in one way or another and yes that suction sound you hear is normal with all the TBI wagons!

Sorry guys,I couldnt let that gas comment go!

If the system is pulling a vacuum on the tank, than change the cap!  It is designed to let air in not out.  Will allow small amounts of pressure, controlled by the canister valve.  The cap is supposed to prevent vacuum.

Bill

Bill so there is a valve in the canister? Is is replaceable? Separate problem, but I think my no long works.

cbshea13 wrote:

So, I paid a visit to Tim today and helped him pull his tank and we swapped (I think lol!) fuel pumps back to the ACDelco (at least that's what when in!).  It seems the check valve on the Spectre was done.  We also replaced the o-ring around the pump assembly.  This time when he keyed it on, the psi shot up to 46.  It stayed there a bit and slowly lowered, but hovered around 40 for the most part.  

My question is this:  Could the o-ring around the fuel pump assembly have caused these problems?  It didn't seem so much as it was "sealing" the pump like with A/C and other o-rings.

By the way, it was great to meet Tim and his family!  He has a VERY fine wagon (yes, I gave the "oh $h*t," when my head snapped on the test drive).  I went from, "so what made you put a manual in this car?" To this....

I want to keep my car stock he says!! LOL! Thanks for stopping by Chris, an extra hand is always appreciated.

So I started taking the tank down and realized that it was full!! So I used the fuel pump to drain the tank. Worked pretty well if I do say so.

I replaced the fuel filter (for grins) and used same pump. The check valve seems to work fine. I did replace the seal where it connects to the sender, but it is not a o-ring. I large rubber seal. I also tried to seal up the schrader valve with a thin layer of silicone grease, but that will be replaced soon. Not sure what I really changed, but it now comes up to 46 psi when pump is running, but car is off (no vacuum). It does leak down after you shut it off. Currently an old used regulator is in the car.

We will see what she is like tomorrow in the AM

There we go! The seal. My apologies! lol. And yes, draining the tank was...different! As I said before Tim, any time. As long as I'm not working, and have child care, I'm up for getting dirty! (Oh and thanks for the lights, will be removing the door panel after dinner to check for wiring! )

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and we fixed nothing!!!  still starting hard!!

has anyone tired the Holley adjustable fuel pressure regulator? Looks like a much higher quality product. This would let me take the FPR off the list of suspects.

Found a nice long read. It almost seems to fit your symptoms at times....at least I think so.

A link is in your private messages!

Read it. I soldered my connections so this would not happen. My issei is not an intermittent pump run, but pressure bleed off.

I bit the bullet and bought new schrader valves (50 so if anyone needs one let me know!), Walbro Fuel pump (US MADE!!), adapter for a permanent fuel pressure gauge and a Holley adjustable FPR. Going to go in steps. I will replace the valve first and see where the pressure is, then the FPR and check it. Lastly the Fuel pump, if all else fails.

It is going to be 2 weeks before I have a chance to work on it though.

Ok so I had some time to dink with it today.

*Inspected/replaced as needed o-rings in fuel rail

*Tested new FPR with a vacuum pump - holds 15psi without fail.

*Re-installed FPR - stock replacement unit

*Replaced schrader valve core
_______________________________________

The GM Factory Service Manual states that with the fuel pump running but engine off the fuel pressure will be 41-47psi. With the car at normal operating temp at idle it should be 3-10 psi lower than your initial pressure. So my car should idle at 34-37 psi approx when warmed up at idle.

- After the system replenished itself with fuel before it started I got 41-42 psi on the rail with the engine in start but not running. When the fuel pump comes on it climbs quickly but stops hard at 41-42 psi. It seems the FPR will not let it go higher than this.

- Tested the pump by shutting off return line - 70psi achieved instantly. So no flow problems in the lines.

- After start up the vacuum line NOT hooked up I get 38-40 psi.

- Install vacuum line and it idles between 32-34 psi. rev it and it bounces off 41-42 and back down.

- Started the car a second time. Removed vacuum line from FPR and shut it down to see if it will hold 38-39 psi that it. Shut the car off.
- Shut off at 38psi
- At 25 minutes the pressure it up to 40psi (I assume you get a little fluid expansion when the fuel in the rails & lines warms up a bit after coming out of the cold tank).
- At 40, 50 minutes still solid at 40psi
- 70 min 38psi
- 90 min 37psi
- 110 min 36psi
- 2 hrs 34psi
- 3 hrs 32psi

Following FSM Chart A-7 it tells me my FPR is bad. It also seems my test gauge is loosing pressure, so time for a new gauge. More to come when I accomplish these to tasks.

For the record, the  curled hose going from the top of the pump up to the bottom of the sending unit tubes has a tendency to crack or blow out, and thus spring leaks. Anyone who has to get into the tank for any purpose should replace it  for  good measure. It's an once of prevention in a twenty five gallon tank.

I left the wagon sitting overnight and most all day. It was at 8 psi when I looked at it (5pm ish). The car started extremely hard. It took 2 cranks.

So sitting beside the wagon in the garage is the Impala. It has the original FPR and original pump (tank has never been down) and 82k on the odometer. It generally starts when the first piston sparks. So this should be my goal.

So to test my drop in pressure I cleaned up my test gauge and it seems to be leak free (no fuel in the pressure release line). So I put it on my Impala (reminder the issues is with the wagon). I left the other gauge on the wagon.

Conditions: No start, but hit the pump to bring the pressure up. The wagon is only coming up to 32 psi when the pump stopped running. The Impala, when the pump is running, not motor, comes up to 44-45 psi. When pump stops it is about 39 psi. So I let them both sit.

Both cars dropped to 24 psi over the period of about 3.5 hours. So it appears that the pressure drop in the wagon is normal. So the pump, lines, and filter all seem to be in spec based on this and the other tests I have done. It has to be the FPR. Agreed?
__________________

car will start with 30+ lbs fuel pressure,.

squeeze off the return overnite,. see if its still hard start.

Good idea nick.

And the saga continues.

I replaced the FPR with another new OEM style unit. Now it gets to 44 ish with vacuum line off and runs at about 36psi. So now I can cross that off the list.

I pulled the relay from the box that runs the pump and broke it so I replaced with new.

Still starting slowly after it sits for a few hours.

Back to square one. I will pull the plugs tomorrow after church and see if any of the plugs are wet, measure the resistance of each injector (the FSM says they have to be within 1 ohm to work properly). Tonight I will read through the FSM to see if I can come up with any other ideas.

Here's an idea Tim... Sell it to one of us!

There is a ball check valve in the pump ( in the tank) as well. it keeps fuel in the line, rather than being unchecked and flow back to the tank when the ignition is off.

Already tested it.

After all you have checked,. i would pull fuel rail and hang it with all injectors in,wrap paper towels around each injector and see if you have a weeper,.
pressure up the system with return line pinched off,.

pulling spark plugs to see if they are wet will only confirm the injectors are/not leaking

didn't i read somewhere about oil pressure and hard starting on an lt1...?

phantom 309 wrote:

After all you have checked,. i would pull fuel rail and hang it with all injectors in,wrap paper towels around each injector and see if you have a weeper,.
pressure up the system with return line pinched off,.

pulling spark plugs to see if they are wet will only confirm the injectors are/not leaking

didn't i read somewhere about oil pressure and hard starting on an lt1...?

I do believe he pulled the number 3 plug while I was there yesterday, and I thought it looked fine (as did he).  I was doing some reading on it (again, lol) and one thing popped up after a few pages... the Mass Air Flow sensor.  One of the symptoms can lead to extended cranking times when cold, and seems to fall in line with the problem Tim is having.  This is one of the few things I think wasn't checked yet.

Spark, fuel and compression are there.  Could it be an air/fuel mixture issue?  Then again, I could be over-thinking it and didn't even consider the injectors.

Edit: I'm just throwing this MAF part out there. I would not have considered it had I not come across a few pages mentioning it.

phantom 309 wrote:

After all you have checked,. i would pull fuel rail and hang it with all injectors in,wrap paper towels around each injector and see if you have a weeper,.
pressure up the system with return line pinched off,.

pulling spark plugs to see if they are wet will only confirm the injectors are/not leaking

didn't i read somewhere about oil pressure and hard starting on an lt1...?

When I started this whole adventure I pulled the whole rail and put blue paper towels under each pair and charged the rail - Nothing!

I know there is a lot of things it could be. I should have an extra oil pressure sensor I might try one.

cbshea13 wrote:

phantom 309 wrote:

After all you have checked,. i would pull fuel rail and hang it with all injectors in,wrap paper towels around each injector and see if you have a weeper,.
pressure up the system with return line pinched off,.

pulling spark plugs to see if they are wet will only confirm the injectors are/not leaking

didn't i read somewhere about oil pressure and hard starting on an lt1...?

I do believe he pulled the number 3 plug while I was there yesterday, and I thought it looked fine (as did he).  I was doing some reading on it (again, lol) and one thing popped up after a few pages... the Mass Air Flow sensor.  One of the symptoms can lead to extended cranking times when cold, and seems to fall in line with the problem Tim is having.  This is one of the few things I think wasn't checked yet.

Spark, fuel and compression are there.  Could it be an air/fuel mixture issue?  Then again, I could be over-thinking it and didn't even consider the injectors.

Edit:  I'm just throwing this MAF part out there.  I would not have considered it had I not come across a few pages mentioning it.

I have a MAF or two around I could swap out. Also if the coolant temp sensor in the front of the pump is not within spec it can cause issues. Lots to look at!!! So little time and patience left.

The one problem I ever had with my Wagon was hard starting. Eventually it turned into No Start. Swapped out the MAF and it never happened again.

Not sure if you have already tried this yet...but have you checked the throttle body?

I ask this because over the weekend I finally had some time to look over my car and perform a little tune up on it. The first thing I did was clean the throttle body. It was filthy! 22 years filthy to be exact. I did a VERY quick cleaning job on it, and now it runs 100 times better. Faster start up, and better idle, and response. No more hesitation during passing, or from a dead stop.

I would give that a shot while you are looking at the MAF. Try cleaning the MAF before replacing it. Also remember that sometimes the computer needs 50-100 miles of driving to re-learn.

Good luck. I know if I was in your shoes I would have thrown a wrench through the windshield....twice.

If you unplug the temp sensor before start it'll think its forty below,.That one experiment to try next time it has sat for a while and before you even attempt to start it,.

if you let the fuel rail sit over blue paper for a while and nothing leaked over time,.,. then pulling the plugs makes no sense,. sorry,.

so humour me here,..  

you know it'll be hard to start after a day or so,.

so,.

If you turn the key a couple of times and cycle the fuel pump and build pressure before you even try to start,.  it doesn't help?

Are you moving the fuel pedal at all when you try to start it?

Another experiment to try after it has sat for a while, is to unplug the maf and see how it starts,
make sure you don't have a tear or an open port between maf and engine, allowing air in after maf has calibrated,.

Is your idle air control working ok?

Sorry for the late response to all this. I was testing the car and my passenger side cat blew its guts into the exhaust pipes, so I was dinking with getting that all cleaned out and while I was at it I sent the headers back to Jet Hot.

phantom 309 wrote:

car will start with 30+ lbs fuel pressure,.

squeeze off the return overnite,. see if its still hard start.

I built a stubby piece of line and blocked it off plugged it into the fuel rail and it instantly went to 70PSI as it should.

Bobloblaw wrote:

Not sure if you have already tried this yet...but have you checked the throttle body?

I ask this because over the weekend I finally had some time to look over my car and perform a little tune up on it. The first thing I did was clean the throttle body. It was filthy! 22 years filthy to be exact. I did a VERY quick cleaning job on it, and now it runs 100 times better. Faster start up, and better idle, and response. No more hesitation during passing, or from a dead stop.

I would give that a shot while you are looking at the MAF. Try cleaning the MAF before replacing it. Also remember that sometimes the computer needs 50-100 miles of driving to re-learn.

Good luck. I know if I was in your shoes I would have thrown a wrench through the windshield....twice.

Already removed and cleaned the throttle body all up and messed up my TPS. So I replaced that.

phantom 309 wrote:

If you unplug the temp sensor before start it'll think its forty below,.That one experiment to try next time it has sat for a while and before you even attempt to start it,.

if you let the fuel rail sit over blue paper for a while and nothing leaked over time,.,. then pulling the plugs makes no sense,. sorry,.

so humour me here,..  

you know it'll be hard to start after a day or so,.

so,.

If you turn the key a couple of times and cycle the fuel pump and build pressure before you even try to start,.  it doesn't help?

Are you moving the fuel pedal at all when you try to start it?

Another experiment to try after it has sat for a while, is to unplug the maf and see how it starts,
make sure you don't have a tear or an open port between maf and engine, allowing air in after maf has calibrated,.

Is your idle air control working ok?

I checked my temp sensor tonight and it tested good. If I cycle the key VERY quickly 3-4 times it starts fine. If I let the pump run until it stops, turn the key off and turn the key back to run the pump does not come on. It will after it sits for a bit. Going to test this against the Impala tomorrow. I may just replace the IAC valve. Both of the ones I have for it seem a bit sluggish. Cannot start it now as I have no exhaust on the car. Testing to resume when the headers come back.

So I got the headers back on the car and started it. Started REALLY hard after sitting for two weeks or so. While the headers were off I replaced the spark plugs with new and gaped each one to .050, replaced the IAC valve while it was down and NO change.

Next I swapped the MAF and the Air intake temp sensor with zero change.

Sunday afternoon I swapped the coil and cleaned up the engine ground - no improvement
That night I swapped out the Opti with a Delco one I had in back stock. Seems to have done the trick. So the old cliche' "Its the Opti" still holds true!!

What brand was the opti you replaced?

DELPHI

BigBlackBeaSSt wrote:

Sunday afternoon I swapped the coil and cleaned up the engine ground - no improvement
That night I swapped out the Opti with a Delco one I had in back stock.  Seems to have done the trick.  So the old cliche' "Its the Opti" still holds true!!  

EH,...????

Sometimes it is the most stereotypical solution that works.

So the opti was degenerating over a few hours?



??

phantom 309 wrote:

So the opti was degenerating over a few hours?



??

I'm not sure how I'd put this.  It seemed to start right up after *fuel pump swap, spark plug swap...etc*  but then eventually start to have the issue.  (I think this is how I'd put it anyway, from what I saw/heard Tim say.  (I was there doing the fuel pump swap one day, and it fired right up after the fuel pump change - only to go back to the problem later in the day.)

Note:  On Monday it started hard again for him, but I don't know if that was before or after the Opti change (I was at work and could not respond to his text, but according to post he changed it Sunday night)

Edit: had to change use of > making my text not appear lol.