88 Delta 88 Starting Problem - Injectors Leaking??

[Ron AKA]

Has 3.8L V8, 150,000 km, and is generally in very good conditon, but has a starting problem which is getting progressively worse. Last winter when temperature got down to -10 deg. C (+15 F) or colder without being plugged in, it would not start. It would fire erraticly but not continue running. Summer came and all was fine until the last month or so. It is now getting down to 0 C at night, with similar issues. Further it has now started to not start even when at normal temps 20 C or 70 F when parked inside. It fires and then spits out the starter, at first only once and then it starts. Now I have to go through this routine many times to get it to start. Also occasionally it backfires during the attempted start. If I stop it after being warmed up and try to start it after 30 seconds it also is hard to start - misfires and spits out the starter gear.

I have checked for codes and there are none. Prior to this getting worse I got the camshaft postion sensor code and replaced the sensor. That has not come back. Changing it made no improvement to the starting problem.

Once the engine starts it runs perfectly. It never stalls, never misfires, and accelerates cleanly with lots of power. Plugs are platinum and were replaced not that long ago.

I have checked the pressure on the fuel rail after the engine has been stopped for a few hours and there is none. Even after 30 minutes there is none. If I check immediately after stopping the enine there is some pressure but not enough to leak any amount of gas out if I hold down the schrader valve.

Could it be that the fuel injectors are leaking fuel into the engine after I stop it? Should there be pressure in the fuel rails after stopping the engine. Is there a good process to check this further, or do I just have to replace the injectors? On the last two tanks of gas I've added a fuel injector cleaner, and over these two tanks the problem has become much worse.

Or, do I have a starter problem? It sounds like one or two cylinders at best try to fire. Should this spit out the starter?

Thanks for any help you can provide. At the rate this is getting worse, I may be walking tomorrow!!!

Ron

[GTP Dad]

Start with a new fuel pressure regulator. It sounds like yours is bad and letting the pressure leak down when you shut the engine off. This would account for the hard starting since it does not hold enough pressure for the injectors to provide fuel to the cylinders.

[Ron AKA]

Originally Posted by GTP Dad

Start with a new fuel pressure regulator. It sounds like yours is bad and letting the pressure leak down when you shut the engine off. This would account for the hard starting since it does not hold enough pressure for the injectors to provide fuel to the cylinders.

That sounds cheaper than injectors. However, if that is the problem wouldn't leaving the ignition turned on for 30 seconds or so before starting solve the problem? I've tried that and it does not help.

Ron

[maxwedge]

Scan the pcm see if the coolant and air intake temp sensors are accurate, tap the maf see if there is any response in the engine at idle, make sure you are getting a signal fom the cam sensor also, the magnets have been known to come loose on the gear.

[Ron AKA]

Originally Posted by maxwedge

tap the maf see if there is any response in the engine at idle

Not sure what you mean by "tap the maf"?

I had an engine warning light come up intermittently over the past year. About 2 months ago I checked the codes and found it was the camshaft sensor circuit. Replaced the camshaft sensor and it solved the code and warning light. Made no noticeable difference to the way it ran. About the only thing I noticed a little different after replacing the sensor was a bit of a misfire occasionally when starting, but it always started. At that time there were no other codes. Will have to check the codes again tonight to see if something else has not come up.

The engine would not start this morning at 4 deg C, so I have to do something with it now and can't procrastinate any longer!!

Ron

[GTP Dad]

As for your question, if the FPR is bad it may take time for the pressure to build up enough for the injectors to work since they take between 45 and 55 psi just to work properly. The FPR is much cheaper than a set of injectors and a lot easier to change than a fuel pump. If the pressure drops as fast as you are saying then that is where you want to start.

[Ron AKA]

Have developed a plan to try and resolve this. One possible cause is a leaking fuel pump check valve. Is this valve part of the pump? If not where is it? If it is in the pump can it be replaced alone or have to replace the whole pump? From my Haynes manual it appears I have to drop the tank to get at it.

Background

I'm thinking there are three possible causes of this non-starting (but runs fine after it starts) issue:

1. Fuel Pump Check Valve leaks $$- This explains the loss of fuel pressure in the rail when shutting down engine. From my Haynes manual it says the pump only runs 2 seconds when the key is first turned on. If the pressure that develops after 2 seconds is not enough to start the engine, the pump never runs again so there is no fuel. If it starts then the check valve is not really needed until the next start.

2. Fuel pressure regulator failed or leaks $ - Similar to the check valve the regulator may be passing too much fuel back to the tank resulting in a low pressure. After the engine starts the ECM goes into closed loop control and may compensate for this low pressure. This may also explain the cold start issue as I expect more fuel is required for a cold start. Further when I replaced the camshaft sensor a few weeks ago, I found the vacuum hose to this regulator disconnected. I have read that the fuel pressure should go up about 10 psi when you disconnect that hose. So when I "fixed" the hose connection I may have made the problem worse. Could explain why the problem got worse so quickly in the past few weeks.

3. Fuel Injectors Leaking $$$ - This also would explain the loss of fuel pressure. However, one would think this would cause some running issues also. Further one would expect this may may the engine easier to start when cold - unless there is way too much fuel and I'm trying to start in the flooded condition.

I'm hoping for #2 due to cost. I think I can narrow it down to 1 & 2 by turing the key on an off several times leaving it on for about 3 seconds each time, and then trying the start. From there hopefully determine if it is the check valve or regulator by pinching off the supply and return lines respectively. Looks like it will cost me a fuel pressure gauge in any case.

Ron

[Ron AKA]

Well I'm getting no where on this problem. Got a pressure gauge and when I first hooked it up pressure comes up immediately when you turn the key on - about 43 psi which is what the book says it should be when the key is on and the engine is stopped. The pressure sags some when you attempt to start it. No luck with starting even when accelerator is on floor. The first time I hooked up the fuel pressure gauge the pressure sagged about 10 psi over 10 minutes and then held.

Cleaned the mass air flow sensor, throttle body as best I could, and the plugs. With a lot of difficulty the engine finally started. Fuel pressure went down to 35 psi from 43. I understand it should go down. When you accelerate the engine the pressure comes up to about 40. Shut engine off and pressure slowly increases to 43 psi from the running 35 psi. Pressure held at 43 for at least 2 hours without dropping.

I think this eliminates the fuel pump check valve, and the pressure regulator. I suppose the injectors leaking and flooding the engine while shut down could still be a possibility, but does not seem likely. The engine now hot, starts on the second try. First try it spits the starter motor out.

I'm out of ideas? Probably will change the plugs although they are platinum and not that old.

Ron

[Ron AKA]

Since last post I discovered that pressure does decay when the engine is hot intermittantly. I've seen it hold fine in some circumstances and decay so fast you can see the pressure gauge needle moving. Pulled the fuel rail and found no leaking injectors. I saw the pressure decaying while the injectors were out and dry. Must be the check valve or regulator. However if I turn the ignition on the pressure comes back up to 43 psi nearly instantly. While the pressure decay is not good, I'm not sure that is the problem.

Went to store to get new plugs. When I came back pressure down to 10 psi and engine cooled some. Installed new plugs and engine will not start. Occasional backfire but no start!!!!! Grrrrrr

Ron

[niemo810]

Ron AKA, i have the same exact problem with my 94 eighty-eight LSS w/ 153,000 mi. when i got the car 3 months ago, no problems at all. although my starting situation isnt as bad as yours, it has gotten worse pretty fast.

i have also tried fuel injector cleaner, and the problem has only gotten worse since then. a cold and snowy western new york winter is coming quick, and i dont want to be left in the cold

i have another problem also, and i was wondering if it was the same for you: when i rest my foot on the accelerator just slightly at low speeds, the car sort of jerks back and forth rapidly.

any help with any of these problems is GREATLY APPRICIATED!!

[exalteduser]

i dont really understand the whole"spitting the starter out thing. do you mean it disengages itself?
because that doest sound too good

anywho, take a look and see if all plugs are firing, maybe it coul be the coil pack being finnicky upon startup check each wire for spark. mine does something like that time to time ill fire it up and maybe i let off the key a sec to early and it just tries to fire but instead backfires and i see a bit of smoke out of the hood compartment then it wont start for a few minutes. but i dont have a clue wat that is. also you could do a injector balance test to see if they are all equal. good luck

[GTP Dad]

You still do not have enough fuel pressure for the car to start properly. Leaking down like you say indicates a bad fuel pressure regulator. When the pump is on the pressure should be between 45 and 58 pounds of pressure. You are only seeing 43 psi with immediate leak down. Give the new FPR a try and I think you will see a big difference.

[niemo810]

thanks to all, i'll post and let everyone know how the new fuel pressure regulator. (not sure when, im running low on cash)

-Rob

[Ron AKA]

Originally Posted by exalteduser

i dont really understand the whole"spitting the starter out thing. do you mean it disengages itself?
because that doest sound too good

I'm starting to think the starter is a good part of my more recent problem. I think the starter overrunning clutch is disengaging much too soon. I was determined to see if I could pull the starter yesterday, but could not get it started so I could drive it up on the ramps. Looks very tight getting the starter out.

Ron

[Ron AKA]

Originally Posted by GTP Dad

You still do not have enough fuel pressure for the car to start properly. Leaking down like you say indicates a bad fuel pressure regulator. When the pump is on the pressure should be between 45 and 58 pounds of pressure. You are only seeing 43 psi with immediate leak down. Give the new FPR a try and I think you will see a big difference.

I would have replaced the FPR yesterday just to see if it was the problem, but no stock in all the parts places I tried. I do suspect the pressure regulator is basically working. The pressure is 43 before starting and goes there nearly instantly on starting. I can hear the fuel pump run now and it runs for about 2 seconds on each start cycle. Running it is about 35 psi. Seems to be right in line with the pressures quoted at this site below 41-47 running, with a drop of 3-10 psi when running. Further it will nearly instantly step up to the +40 range if you jerk the throttle open while running (dropping vacuum). Similar if you disconnect the vacuum hose.

http://www.autozone.com/servlet/UiBr...3d8015e782.jsp

Thanks for the help on this. I starting to think the starter itself is the bigger part of the current problem. Should not spit out so easily.

Ron