brotherfak

Ok, where to start.
so my 87 C4 will not start, when it does it runs rough then dies. after that it is very difficult to start.
what I have replace.
ELECTRICAL:
Spark Plugs, plug wires, ignition coil, rotor, cap, ignition module.
FUEL:
Fuel Filter, Fuel Pressure Regulator, Fuel Pump Filter.
AIR:
Mass Air Flow Sensor, air filter.
I Have tested all the injectors, fuel pump relay, MAS relay, and they all test ok.
Now to the good stuff. When I start the engine sometime it will start. it idles rough then dies. when it dies I can hear clicking in the engine compartment. when the key is turned on and not running I hear random clicking. sounds like the fuel injectors. I have inspected all the air lines and they seem good. unplugging sensors like the TPS or MAS. has random effects but does not solve any problems.
When I turn the key on the fuel pressure rises to about 40# then clicks off and immediately drops to 20-15#. when the car does run it hangs out around 40# but pulses.
now I reach out to you forum for any help.
Thanks,

don hall

'check engine' light 'on' - any codes?

brotherfak

Ahh, yes the codes. I just went and pulled the codes, 32 and 34.
of course 34 was the reason I replace the MAS in the first place. it comes and goes as I reset them. 32 is always there.
In other note I just started the car and it fired right up after sitting all night. ran for about 2-3 mins then quit. rough idle. I restarted it and gave it a little gas. about 2200-3200 rpm I kept it there and about 2-3 mins it Died.

cmontel727

At this point I would check your fuel pressure, put a tester on the schrader valve on the fuel rail. Pressure should be around 43psi at idle, report back your results.

The codes you are getting are for the maf and egr. Did you check or replace the maf relay? This ten dollar part can cause the dreaded code 34? Have tried running the car with the maf disconnected?

brotherfak

I have initial pressure of 38 when the key is turned on. then it immediately drops to 20 then slow to 0. Now when the car is running it is at 38-42. the needle bounces in this range.
I have not replaced the sensor but I did test it and it seemed fine. I will try replacing that as well.

brotherfak

another symptom that may help. When the key is in the on position and not running. I will hear random clicking. it sounds like the Fuel injectors are firing without the car running. hope this helps.

C4SS

Sounds similar to my '88 quitting problems.
I'll be watching for your eventual solution.

brotherfak

I take it you never got your 88 fixed.

C4SS

I'm currently working on it. I'm getting some good
advice from forum visitors.

C409

........ Did you OHM check the injectors ? Multecs should be very close to 16 ohms ... since they are batch fired , if even one injector is bad it will electrically affect all of them ........

brotherfak

I did ohm them all. 16 ohms all 8 of them.

Cliff Harris

Seems unlikely. The ECM uses DRPs (Distributor Reference Pulses) from the ignition module inside the distributor to synchronize the pulsing of the injectors to the rotation of the engine. Without those DRPs (engine not rotating) the injectors should not pulse.

I suggest poking around with a mechanic's stethoscope or a length of hose to localize the source of the clicking.

C4SS

Have you found the solution yet? I haven't found mine yet, but
I'm looking at the TDM system; theft deterrent module.

Here's a test, if you have a second key, try it. The chips in them
go bad sometimes and affect starting and running.

cmontel727

Ok the running fuel pressure is good. The next concern I have is that your fuel pressure drops out that quick when you put the key on. Usually when that happens it is one of three issues; bad fuel injectors; bad fuel pressure diaphragm, or a bad check valve on the fuel pump. I'm going with the fuel injectors being problematic, since you replaced the fuel pressure regulator diaphragm and the fuel pump check valve is rarely the culprit.
How old are the injectors? Are they the original mulitecs? Did you ohm them hot after the engine dies?

If you have the FSM you can run various tests to determine which part is causing the quick pressure loss. The test involves pinching off the supply line and then checking fuel pressure loss and then the same procedure for the return line.

I would still try to run the engine with the MAF disconnected, this can help rule out problems in that area as well.

The clicking you are hearing is a concern as well. I would try to trace where this noise is coming from as well.

My car did not run right until an injector change, the original multitecs were the problem. The funny thing is the ohms were in spec when tested.

brotherfak

I think it would be best if I changed the Injectors. I wish I would have don't that while I had the fuel rail off in the first place.
I did ohm them hot 16 ohms.

The injectors are firing when the car is not running. I have not connected an anoid light to it yet but will soon and video it to post on YouTube. in addition I plan on removing the ignition module again (this is a brand new one) and having it tested or replaced.
Looks like its back to the garage for me.
Thanks for all the advice.

Tom400CFI

IF this is true, I'd be seriously scrutinizing the pick up coil and associated wiring going to the ECM. I'd also be scrutinizing the ground side of the injector harness for shorts to ground.

brotherfak

Any suggestions to test either of those issues?
Now that I think about it I replaced the pick up coil as well.

Tom400CFI

Not really, The pick up coil isn't likely going to generate a pulse w/o the distributor shaft rotating, but I'd still visually inspect it. More likely I'd inspect the injector harness for shorts to ground. A short to ground, on the ground or "signal" side of the harness would activate the injectors when the key is on (power to the injectors).

VikingTrad3r

this^^^

and check your fuel pressure regulator. u said your fuel pressure "bounces" around. never seen it do that unless ur are pulsing the throttle. might just be injectors but it takes 30seconds to check it. pull hose and see if it smells like gas.

brotherfak

I just replaced the FPR and I took extreme care not to damage the diaphragm. there is also no smell of gas in the hose.

I did pinch the intake fuel line and got no pressure at the fuel rail. then pinched the return line. now when I turn the key the pressure goes to 38-40#. then clicks and goes to zero. even with the return line pinched.
now if I turn the key on to get pressure then immediately turn it off the pressure holds I did this 3 times and got to 60# at the rail. with the key off it held steady until I released the return line.