L05 sporatic missing/sputter NO check engine light

The problem:
The l05 in my '92 wagon will miss sporadically and fall flat on its face. but not at all RPM ranges. 1500 to 2000 seems to be the worst or anytime when the load increases (going up a steep hill, leaving "hard" from a stop) this usually only happens after the car has been running/driving for about 5-10 min. just enough to see the heat gauge move up. it sometimes worsens as the engine approaches normal operating temp. it has occasionally done this cold as well. there is no check engine light. once in a while it runs perfectly.


New parts within the last year under 10000 km (about 6000 miles)
Champion wire set
Champion cap and rotor
AC delco plugs
air filter
O2 sensor (less then 1000 km ago)

right now im thinking it could be the coil.

Also, i dont know if it's normal or not, but when its cold i need to crank the engine for about 3-4 seconds before it starts. when warm it will start right up fast. it's done this since before i bought the car, i always assumed it was normal....

That sounds like either a dirty fuel filter or the fuel pump is on its way out.

Mine also acted that way when the clamps broke loose on the hose from the fuel pump outlet to the fuel line (in the tank). It would start immediately after a shut-down, but let it sit overnight and it would require several seconds of cranking before it would start.

Dying fuel pump. My 92 RMW behaved the exact same way.

the llong crank when cold seems normal. I've had 4 tbi wagons and all the same even with a brand new fuel pump.

rest of the symptoms, agree the FP is dying, at least your lucky it's giving you a warning. Sometimes they just GO for no reason (ask me how I know)

Fuel related, makes sense. i'll check the cars history, i think it's fuel filter is long over due i'll do that first... i really dont feel like dropping the tank

it was acting up REALLY bad tonight, after 2000 rpm i could hit the gas and the RPMs either wouldn't change or there would be a big hesitation.

as for the long crank on tbis, my brother has a '91 s10 with the tbi iron duke 4; i know, completely different animal. But it acts the same way as far as starting goes.

Dont know if yours is original but it sounds like the catalytic convertor is giving up on you!
Benn,do you notice any odd,potent,make your eyes water kinda smells?

Flasheroo wrote:

Dont know if yours is original but it sounds like the catalytic convertor is giving up on you!
Benn,do you notice any odd,potent,make your eyes water kinda smells?

like rotten egg smell? no none really.

I found that the cat will just limit performance in an even manner. The fuel pump can be anything from a miss to sporatic running conditions, to just letting you sit somewhere. I have AC delco pumps in both of my cars, and I am not sure they are any better than some of the others. The AC Delcos would be nice if they pushed a little more pressure (my gauge says that I have less pressure than I should). If the fuel pressure is low, the car will not run right above the level pressure needed for the HP produced. It is almost impossible to check the fuel pressure, but there is an adapter available, although you have to rebend your fuel line to make it fit. I have installed it on one of my cars with a mini fuel pressure gauge, and it is nice to know what the pressure is.

I spent a lot of time and money because I did not want to drop the tank. When I finally did, I found the hose between the pump and exit tube was cracked. Sometimes the car would run, and sometimes it would just let me sit. Totally unpredictable. I swapped the hose, and about a month later the pump quit. If you go into the tank, replace the pump no matter what. I have had my tank down 4 times now. Once for the hose, once for the first pump, once for the second pump (30 days later to replace the Bosch pump that failed) and a year and a half later for an AC Delco pump (to replace the 2nd Bosch pump that failed).

my wagon has the same issues.. just replaced the coil.. not it.. i would like to say about 8months ago i dropped my tank and replaced my fuel pump(acDelco) because it went on me.. so that cant be it.. plugs and wire ares new as of my rebuild about a year or two ago.. brand new fuel filter.. not it.. spayed all my wire with a mist bottle to see if i can see something my eyes couldnt with water.. nothing.. i changed the distributors ignotion module.. not it.. cause when it had died on me a month or two ago it would start back up.. but it did work when i installed it.. it runs now.. my only isse im having more then you is when im in a parking lot as im making a turn or something sharp turn my wagon dies on me.. like the power steeting pump draws too much.. so to me the only thing that could be left is a cracked fuel lines(fuel isse you guys are talking about) or a ground or electic issue.. but my battery is about two years old and an acDelco.. could be but debutable.. this issue is killing me!.. but back to the fuel line isse.. i dont smell or see any leaking spot on the rear of the tank and fuel lines on the frame look clean..

i even pulled all my plugs out and they where a little black.. nothing crazy.. they are all gaped good.. cause maybe the injectors being clogged?.. i never had to deal with an injector problem.. so i wouldnt know any of the sythoms for that.. pulled the cap and rotor.. the cap had some corrision in it.. nothing crazy.. cleaned it anyways.. and still the same problems..

I had this problem with Ms. Roadie. Turned out to be a bad fuel pump. The pump would not provide enough fuel flow. You can test for this by testing the fuel pressure while running (9-13 PSI), then pinch the return line and see if the pressure spikes and holds. If it does not then the pump has a bad relief valve. Another thing to do is a leak down test. Again check the pressure while running (9-13 PSI), shut the car off and see how long it takes for the fuel pressure to drop to zero. Should be a slow steady decline (3 plus seconds). If it drops to 0 in less than two seconds there's a good chance the relief valve is bad.

Be very careful if you use the fuel pressure tester that includes the adapter which connects inline between the fuel line and the fuel pod on the TBI. The Aluminum composite threads are softer than the brass threads on the adapter, ask me how I know this?

I found the best way to install the adapter is to remove the tbi from the intake. Gaskets are cheaper than fuel pods, I'm sure you can guess how I know this. Install the adapter between the fuel pod and fuel line. Don't tighten the fuel line/adapter threads all the way. Install the the TBI back onto the intake manifold. Tighten down the fuel line/adapter connections. Make sure the nipple/schrader valve is positioned where you can connect the fuel pressure tester hose easily, and proceed with testing. When you're done testing just disconnect the fuel line, and remove the adapter. It comes apart easier then it goes together. You shouldn't have to remove the TBI to get the adapter off.

When that's all finished enjoy dropping your tank and replacing the fuel pump.

WagonLover;
I'd start by putting a fuel pressure gauge on it and see what's happening to fuel pressure when it acts up.

A new fuel pump could fail that quickly, but there are many other possibilities; a leaky pump output hose, corroded fuel lines on the sending unit, bad fuel pressure regulator, dirty/clogged injector(s), intermittent electrical open circuit in the ESC circuit and on and on and on.

Don't keep spending money on parts until the problem is properly diagnosed.

scoffman - can you post pics on where this gauge could go in the fuel lines?..

JoeT - i agree.. but i always see it as its my baby and it needs it anyways.. yes a horrible way to diagnose a car.. totally agree.. huge money pit but its all i got!

scoffman wrote:

I had this problem with Ms. Roadie. Turned out to be a bad fuel pump. The pump would not provide enough fuel flow. You can test for this by testing the fuel pressure while running (9-13 PSI), then pinch the return line and see if the pressure spikes and holds. If it does not then the pump has a bad relief valve. Another thing to do is a leak down test. Again check the pressure while running (9-13 PSI), shut the car off and see how long it takes for the fuel pressure to drop to zero. Should be a slow steady decline (3 plus seconds). If it drops to 0 in less than two seconds there's a good chance the relief valve is bad.

Be very careful if you use the fuel pressure tester that includes the adapter which connects inline between the fuel line and the fuel pod on the TBI. The Aluminum composite threads are softer than the brass threads on the adapter, ask me how I know this?

I found the best way to install the adapter is to remove the tbi from the intake. Gaskets are cheaper than fuel pods, I'm sure you can guess how I know this. Install the adapter between the fuel pod and fuel line. Don't tighten the fuel line/adapter threads all the way. Install the the TBI back onto the intake manifold. Tighten down the fuel line/adapter connections. Make sure the nipple/schrader valve is positioned where you can connect the fuel pressure tester hose easily, and proceed with testing. When you're done testing just disconnect the fuel line, and remove the adapter. It comes apart easier then it goes together. You shouldn't have to remove the TBI to get the adapter off.

When that's all finished enjoy dropping your tank and replacing the fuel pump.

The steel OEM adapter has even harder threads than a brass adapter. The one I used is from [You must be registered and logged in to see this link.] is steel, and it is a permanent installation ($35 + $15 for a mini gauge). I did the mod in about an hour. To make it easy you can remove the entire line, after making a wire form to copy for the angles you want. You unbend the line where it turns away from the head, and increase the bend at the end where it turns toward the TBI. You may have to tweak it a little once it is in the car, but it will bend enough to fit. I can take a picture for anyone who wants to do this, to give you an idea of what the installation should look like.

I had a similar miss. It took about 5-10 minutes to feel it. Sometimes - no miss at all. I thought it was the fuel pump but I opened the hood and found a loose spark plug wire at the distributor!

It was barely attached. I reconnected it and it has not been a problem since.

didnt get around to it this past weekend. busy with school. temperature has dropped like crazy here, typical. i'll try to get around to it this weekend unless it leaves me stranded sooner.

When mine died, I got exactly one extra drive out of it by hitting the bottom of the tank. Then, it died on the way to work. I parked it on the side of the road, and walked to the parts store. Had the tow truck pick me up there.

just throwing this out there... i took the car out tonight to put some gas in it, on the way home i floored it. held it there for a good 2 seconds and the rpms didnt change, still held it to the floor and all of the sudden the engine woke right up and tapped 5000+ rpm easy. once it shifted and the rpms went back down it started to struggle again. to me it doesnt make sense that a bad fuel pump could cause it to struggle at lower rpms yet it's still able to reach redline. i always thought the opposite.

anyone have any insight towards this? as an added note could an egr valve cause these symptoms? no check engine light so i doubt it. but the cars exhaust smell reminds me of when my parents old truck had a bad egr. sorta like jim was sayng except i have a newer catalytic converter so im doubtful its clogged.


Also, just finished looking through its maintenance history, last fuel pump was in 2006 @ 260,000 km. last filter and sending unit service ("cleaned and sandblasted sending unit.") was in 2009 @ 295,000. thinking its about time i do the pump and especially the filter regardless.

Depending on the position of the fuel pump, a crack in the hose can open and close. The pump is under different loads, and sometimes it will twist into different positions. The EGR should throw a code. The only thing that I know of that does not throw a code, and causes erratic running, is the pump connector hose. It appears that you have swapped out anything that would be related to the issue except the fuel pump. It also sounds like the same problem I had with The White Elephant when the hose was cracked. Sometimes it ran, sometimes it did not, and there was no rhyme or reason to it. The idle also would swoop up and down, as the pump twisted and untwisted the tube.

shucks!.. gotta drop the tank.. running until i run out of gas

just throwing it ouy there.. they always told me there is no such thing as a stupid question.. what about the idle air control deal?.. my buddies neon was always at bad idle until he put an idle air control in.. i know it might not be a chevy but still the same concept at low RPM's?..

I hope you run out of gas in the driveway, and not halfway home.

I took mine out with about a fourth of a tank, removed the hose assembly, and stood it on the passenger's side, then siphoned the fuel into a container. As the container filled, I raised the tank on a small stool to get the level above the container. It gets lighter as it emties, so it is not too difficult to lift. If you have a helper, it is easier too. I did mine by myself, and it was not too bad.

Benn, it really sounds like a fuel pump issue. Bite the bullet, drop the tank and replace the pump and sending unit.

You do not have to replace the sending unit if it is functioning properly. The pump and hose are the issue. Plan on replacing the sock as well, or the pump warranty may be voided.

water in the fuel?

nick

phantom 309 wrote:

water in the fuel?

nick

Chance of water in the fuel causing the problem .01%

Fred Kiehl wrote:

phantom 309 wrote:

water in the fuel?

nick

Chance of water in the fuel causing the problem .01%

where you come up with that %?

he lives in ontario with the wild temp swings frost builds in the tank,.

you florida boys know nothing about cold weather driving,.

go pull your old hose out check it for cracks,.

Where have you been buying your fuel? what grade of fuel are you putting in? what's the alcohol content? how often do you drive the car between fuel stops? The low grade fuel off the native reserves, or the cheap low grade fuels accross the boarder can cause these same symptoms.

both the ratmaster and my dead 91 used to behave like your symptoms if I ran low octane grade fuels with high alcohol content. Real gas with higher octane and less alcohol cured them.

with the drops in temps in the past few weeks you could have a condensation issue.

like Nick says check your old fuel lines, change your fuel filter.

last two fill ups were from Petro Canada and shell, always regular. i put $35 of regular from shell in last night. (just below 3/4 of a tank now) today theres a noticeable change in performance still sputters a bit. dont know if it has to do with the gas or just the pump having a better day. gonna buy a new fuel filter today, hopefully get around to doing it before the weekend.

these cars don't like being below a quater tank

some here will claim that being low in fuel can cause the pump to prematurely fail since they think being submerged in the fuel somehow keeps the pump cool at it's optimum operating temp...

if there is any contaminates in your tank, being that low in fuel better the chances that you could be clogging your fuel pick filter.

yea ive been running it very low the past month or two. moneys got tight. was only putting in about $10-$15 at a time. makes me think all the **** that gathers at the bottom of the tank is now either clogging up the filter or messed up the pump somehow.

i was told its not worth it to run premium and the middle grade stuff is apparently garbage.

benn wrote:

yea ive been running it very low the past month or two. moneys got tight. was only putting in about $10-$15 at a time. makes me think all the **** that gathers at the bottom of the tank is now either clogging up the filter or messed up the pump somehow.

i was told its not worth it to run premium and the middle grade stuff is apparently garbage.

When I ran the wagon in the winter I would put in 89. Got 1-2mpg better and idled better in the cold.

In the US, the regular gas is regulated to government standards. It must work in all government vehicles and not cause problems. Hess got in trouble because they did not put the required additives in the "regular" gas. Lower octane gas actually has more gasoline in it, and less additive. They are both filtered the same, and the lower octane gas should give you better mileage than the higher octane fuels.

Fred Kiehl wrote:

In the US, the regular gas is regulated to government standards. It must work in all government vehicles and not cause problems. Hess got in trouble because they did not put the required additives in the "regular" gas. Lower octane gas actually has more gasoline in it, and less additive. They are both filtered the same, and the lower octane gas should give you better mileage than the higher octane fuels.

And Benn is in Ontario so US fuel has nothing to do with his issues.

And in any event just because gas is regulated doesn't mean stores don't sell junk gas. Two years ago a local discount chain was caught watering down their gas in order to buy less fuel from their distributors.

As for mileage for various octanes, my DD "requires" 89. I get better mileage with 91 and 93 than I do with 87/89. The wagon gets better mileage in winter with 89. Care for me to post the numbers?

Figured i'd try what cadet was saying in put in a full tank of mid grade in. the sputtering problem appears to have disappeared almost completely still a little chugging but overall its night and day.

I think i've been getting bad gas. (does that mean im getting old? ) Because other then my previous top up at petro canada the other week, i've been putting in $10-$20 here and there from the shell near my house. they've had problems in the past with water, wondering if they still are... i'll change the fuel filter this weekend maybe that'll solve the last of my sputtering issues.

heres hoping its not just the pump having a good day.

Good to hear. Also, maybe try a bottle of fuel system cleaner. Chevron is my personal favorite.

ok team, heres my input because I just went through ALL of this...

car falls flat on its face on take off, and shifting to 2nd, then a miss while driving normal, yet pulls strong under WOT...

Codes were set for MAP, TPS, o2, ESC, so I change the sensors, improving things and eliminating codes...

unplugged EGR, ran the best..almost perfect, until a stupid noise came out of the timing chain cover...

go into the timing cover, find the cam sprocket bolts loose, and a VERY loose timing chain...change timing chain and sprockets, put it back together and the car runs like new..

And it better...22000 original miles on this thing...I was just shocked these problems could be on a car with such low mileage..fixed now though.

my egr has been unplugged and capped off since i bought it. throughout all of this the egr code was the only one being thrown.

as far as the timing chain issue did you hear a weird tinging noise at just idle or throughout the entire powerband?

started at idle, rev it a bit and it would go quiet..I couldnt look into it right away because I was away from home...so I had to drive it...3 hours of driving later the noise was there all the time...because the bolts were all working their way out...

the noise sounded exacly like a fan blade slightly touching something... A real tinny, hollow sound..