Miss that is developing? (Help)

[TFENT]

Newest update 9-10-10

OK so tonight I checked the Fuel Pressure of both the new primary and secondary pumps. Both are pushing 50+ without the engine running.

That?s the good news. Bad news is the car will only start after its been sitting for an extended period of time. After 15-20 mins of checking the fuel pumps it will not start. So I took the opportunity to check the spark at each cylinder. Some were VERY blue several are orange and one was yellow. I know this is enough to warrant new coils, which I have ready to install, but it does not make any sense that the car refuses to even want to start. And when it does run its very poorly and throws a lean code.

This leads me to believe that there is something preventing the fuel injectors from firing. These are brand new injectors from FIC. I was told this is a new line of injectors available from only them and here is the link for them. http://fuelinjectorconnection.com/sh...&productId=208 even Marc H hasn?t heard about these yet.

Now I don?t know how to go about checking to see if these are actually working or not. I am going to pull the plenum once again tomorrow and at minimum change out the coils but besides checking the ohms on each injector how do I test to see if they are actually firing??? I am thinking these are my problem?

Thoughts??

[TFENT]

Changed the coils today. MUCH better BUT still have an occasional miss AND it sometimes throws a code 55 lean. So I hooked up the fuel pressure gauge and ran it for a few 120mph+ WOT runs and the pressure is 55-60psi at WOT. On one occasion I downshifted to pass someone and it bogged out and threw the 55. Then ran terrible till I got back to the shop and started to miss-fire for a few mins. Then cycled the key checked the code and went for another run. Ran perfect till I let it sit and idle. It misses still....

I am thinking I have a bad injector or two...

Thoughts?

[Paul Workman]

Originally Posted by TFENT

Changed the coils today. MUCH better BUT still have an occasional miss AND it sometimes throws a code 55 lean. So I hooked up the fuel pressure gauge and ran it for a few 120mph+ WOT runs and the pressure is 55-60psi at WOT. On one occasion I downshifted to pass someone and it bogged out and threw the 55. Then ran terrible till I got back to the shop and started to miss-fire for a few mins. Then cycled the key checked the code and went for another run. Ran perfect till I let it sit and idle. It misses still....

I am thinking I have a bad injector or two...

Thoughts?

For one thing, the fuel pressure escursion to 60 psi = not what the book says it should be! Kinda sounds like a pressure regulator is out to lunch, which would account for a plethera of bogging, and lean and loading up (resulting in a miss at idle). Make sure the vacuum hose is connected properly to the FP regulator. If in fact it is, then that regulator needs to be changed. According to the FSM, 50-52 ish is the ceiling, and it should remain steady at WOT - the ECM is counting on that (especially in WOT/open loop condition!).

If in fact the FP reg is at the root of the evil, I would expect to see some pretty sooty plugs too. It might be worth pulling them and seeing what is going on.

In any case...one problem at a time, the FP thing is important, methinks!

P.

[XfireZ51]

Check to see if there's gas in regulator. Could be damaged diaphragm

[TFENT]

Well Paul. It's all over the place while driving it but when you step on it the needle bounces like you hooked it up to a vibrator. from high 40's to the 60 mark. NOT steady at all.

The Vacuum line is hooked up and in perfect shape. i triple checked. it.

Plugs are very sooty and the sometimes the car starts and sometimes it doesn't. Sometime when its cold some time when it's not cold. Just as it will sit there and idle for 5 mins perfectly then it will miss and just stall. Sometimes it will idle for a half-hour and be fine one min and then just start missing all over the board. Tried seeing what cylinders it happening to in case it was a bad injector or two but seems that when we are trying to track it that cylinder you are at is the dead one. on all but just a few and those ate 7 and 8. Closest to the regulator and fuel supply... hmmmmm

[TFENT]

I haven't touched the car in a few days and now it won't start at all. Cranks but no start...

Does anyone have an ECM i can borrow???

[tomtom72]

I have a spare ECM for my 90. Yours is a 91?, sorry i don't remember. Anyway, I have a spare ECM and an OEM 90 1st design chip, AUAH configuration. Let me know and in the mean time I'll go dig out my spare ECM. It may be that my spare is good up to a 92, I have to run down the p/n to be sure on that issue but I know it is good for a 90.

Secondly. and no offense meant by this. It seems that you are dumping fuel if the plugs are sooty. The injectors could be sticking open? The hard restart symptom is one sign of leaking injectors.

Also, another issue is the bouncing F/Pressure readings. I swapped a new pump/sender unit into my car this yr and my readings were kind of like yours with the bouncing when running. I just had to flatbed her home and when I pulled the pump unit from the tank I found one of those black plastic clamps had a crack in it. It was the one at the "out" pipe. No fuel = no start. I wonder if the cracked plastic clamp was the reason for my bouncing F/P readings. Just a thought.


Tom

[XfireZ51]

Tom,
Lgaff had that same problem. Plastic clamp not holding allowing some of fuel to spurt back into tank. Replace with real hose clamps.

Originally Posted by tomtom72

I have a spare ECM for my 90. Yours is a 91?, sorry i don't remember. Anyway, I have a spare ECM and an OEM 90 1st design chip, AUAH configuration. Let me know and in the mean time I'll go dig out my spare ECM. It may be that my spare is good up to a 92, I have to run down the p/n to be sure on that issue but I know it is good for a 90.

Secondly. and no offense meant by this. It seems that you are dumping fuel if the plugs are sooty. The injectors could be sticking open? The hard restart symptom is one sign of leaking injectors.

Also, another issue is the bouncing F/Pressure readings. I swapped a new pump/sender unit into my car this yr and my readings were kind of like yours with the bouncing when running. I just had to flatbed her home and when I pulled the pump unit from the tank I found one of those black plastic clamps had a crack in it. It was the one at the "out" pipe. No fuel = no start. I wonder if the cracked plastic clamp was the reason for my bouncing F/P readings. Just a thought.


Tom

[TFENT]

Originally Posted by tomtom72

I have a spare ECM for my 90. Yours is a 91?, sorry i don't remember. Anyway, I have a spare ECM and an OEM 90 1st design chip, AUAH configuration. Let me know and in the mean time I'll go dig out my spare ECM. It may be that my spare is good up to a 92, I have to run down the p/n to be sure on that issue but I know it is good for a 90.

Secondly. and no offense meant by this. It seems that you are dumping fuel if the plugs are sooty. The injectors could be sticking open? The hard restart symptom is one sign of leaking injectors.

Also, another issue is the bouncing F/Pressure readings. I swapped a new pump/sender unit into my car this yr and my readings were kind of like yours with the bouncing when running. I just had to flatbed her home and when I pulled the pump unit from the tank I found one of those black plastic clamps had a crack in it. It was the one at the "out" pipe. No fuel = no start. I wonder if the cracked plastic clamp was the reason for my bouncing F/P readings. Just a thought.


Tom

Tom:

Thank you for the assist. It is a 1990

In addition we replaced both fuel pumps a few weeks ago trying to solve the miss/no start. All the clamps were replaced with metal worm gear clamps. The whole assembly was in very good condition and I had a brand new one standing by to go in if it wasn't.

Fuel Injector Connection just sent a whole new batch of Injectors. So I am hoping that I had several bad injectors and a bad Fuel Pressure reg. because this is really irritating me to no end. Plenum pull #5 coming soon.

[Paul Workman]

Originally Posted by TFENT

Well Paul. It's all over the place while driving it but when you step on it the needle bounces like you hooked it up to a vibrator. from high 40's to the 60 mark. NOT steady at all.

The Vacuum line is hooked up and in perfect shape. i triple checked. it.

Plugs are very sooty and the sometimes the car starts and sometimes it doesn't. Sometime when its cold some time when it's not cold. Just as it will sit there and idle for 5 mins perfectly then it will miss and just stall. Sometimes it will idle for a half-hour and be fine one min and then just start missing all over the board. Tried seeing what cylinders it happening to in case it was a bad injector or two but seems that when we are trying to track it that cylinder you are at is the dead one. on all but just a few and those ate 7 and 8. Closest to the regulator and fuel supply... hmmmmm

One crisis at a time, I recon!

First, that fuel pressure thing needs to be resolved. Sounds like a new regulator is in order.
Second, you might either clean and install or buy some standard (AC Delco) plugs and begin again with a fresh, clean set. Then we can go from there.

FWIW, with the fuel pressure all over the map, the fuel flow is too, and the ECM and O2s are not able to provide accurate fueling information - mostly rich, is my guess, which will foul the plugs to the point it may well be a subset of your starting probem.

Just my 2 cents.

P.