Hi all, what signal, input ,etc., pulls in the fuel pump relay. The car will crank/roll over but no 2 second prime and no start. Fuel pump will work if I back probe the relay and at the FP fuse. Also the AIDL test connector seems to be dead cant check codes etc. . ECM seems to be ok gathering from the wires that I check to see if the CCM was getting power using the FSM. The car used to start and then it stopped.

 

What year car is it. Can't get to specific if no year is shown.

The ECM turns on the FP for the 2 second prime. If you are back probing the FP relay and it starts, check for bad pin connections or bad wire crimp.

 

Sorry. It's a 1990

 

And it doesn't start, just cranks even if I build up the FP by back probing it still won't fire.

 

sounds electrical.

check fuses
check fuel pressure while cranking
if you are getting pressure while cranking, but you are not getting the 2 second prime via the fpr, replace the fpr?

but should still start even without fpr via the oil pressure backup maybe just a long crank

so check fuel pressure while you are cranking. if you have no pressure while cranking, maybe you have a dead fp. or a blown fuse to the fp. you might try checking voltage feeding the fuel pump. IF YOU DO THIS, BE VERY VERY VERY CAREFUL AND DO NOT DO IT WITH OPEN GAS FUMES. SPARKS CAN CAUSE EXPLOSION AND IF YOU HAVE FUEL PUMP OUT OF THE TANK AND THEN CHECK THE VOLTAGE FEEDING FUEL PUMP AND CAUSE SPARK YOU COULD GO BOOM.

i never would have given that warning until yesterday where i learned i should not be using electrical gadgets inside the shacks on some of our wells.

if you are getting weak fp while cranking, maybe you have a clogged in line fuel filter or maybe a clocked fuel filter sock filter.

if you confirm fuel pressure at rails, then suggest you check for voltage going into, and out of, the distributor. coils might be shot. you will need a multi meter.

that is the limit of my knowledge here as i have not had to ever do this stuff but have only read about it on the forum.

 

Before going to much further on the fuel situation, and in regard to what has been said, I would check for spark at the plugs. You might have a higher level problem other than fuel.

If you did what you said and ran the pump, then you pressurized the system. It should have started if all else was working.

Checking the fuses for the ECM sure would be a first step. If you do not have spark, fixing that might alleviate the fuel pump (relay) problem.

If the engine was running forget about a fuel clog anywhere. A clog might cause you a runability problem but it should still start up.

 

Just a little info on this car, that might help-I picked the car up from a guy that lives in a wet environment where it sat for 2 years in his driveway ,uncovered,it was full of mold. The fuel line was frozen and ice in the tank. I drained everything, cleaned the tank, repaired the ruptured fuel lines, install new fuel filter, battery, and started the car-had a miss, two fuel injectors not firing,replace with all new 24LB fuel injectors and restart all not bad. Dropped the steering column to remove dash ,for repair then no start .Fuel pump not priming so where does signal to prime the pump come from ?????? .When this happens I check the injectors and spark with node light and spark tester and all seems fine.

 

 

Hi

The diagram is from an 85, however the fuel pump relay and wiring may be helpful.

You will need to check the green/white for 12volt supply from ecm.

Hope it helps you.

 

It sounds like something other than fuel pressure.

On my '88 the fuel pump relay was bad. The car will still start (after cranking a bit) and run fine. The relay energizes the pump for startup. Once the oil pressure rises, the pump will turn on even when the fuel pump relay is not working. It takes 3 or 4 seconds of cranking for oil pressure to build and turn on the pump.

Also you stated that you manually made it run to pressurize the fuel system, so that means it is not a fuel pump/pressure problem. It could be injectors or spark, but it sounds like you have checked them, so I am not sure what else to try.

Good luck.

 

I had my fuel pump die a couple of weeks ago, the symptoms were hard starting and no power under load. You could hit a bump and it would work again, then fail over the next bump.

Is easy to check, you can remove the cover over the fuel pump relay.
Two clips hold it together, use a small screwdriver to remove the cover.

You can then use a volt meter, check you have 12 volts supply to pump when you MANUALY push the contact closed.

(a small cable tie fits perfectly, insert it between the normally closed contacts to close the normally open contact) The fuel pump will work or its dead.

They are cheap and do not last forever, my last forever.

 

Before you start pulling things apart, spray some starter fluid into the intake to verify whether or not the car starts. If it does, then start checking the wiring. If it doesn't. Oh boy. And make sure the fuel pump connector inside the fuel tank is in one piece. Easy to miss. Guys...is the fuel pump relay the same as the MAF relay? I cannot remember. If it is, try swapping them to see if the relay is bad. There are two pins in the ALDL you can jump that should cause the fuel pump to prime. Cannot remember which two. Will need to look that up. No starts really suck!

 

OK. It is terminal G. You supply battery voltage to terminal G and the fuel pump should energize. It should supply 1/2 pint of fuel in 15 min. You just want to make sure it works.

 

The ECM turns on the fuel pump relay.
The ECM makes the ALDL connector work.
The ECM controls the SES light.

Have you noticed a common connection here?

This diagram is for my '86, so the ECM pin numbers are different, but the connections are the same. The main ones to check are the ECM fuse and the fusible link that powers the ECM:

 

Yes and here's what I did. I went back over just about everything that I had done up to when the car used to start and stopped. All the grounds all the movement of wires all the changes like disconnecting the AIC the installation of a new EGR valve, etc. The FSM does point to the ECM operating everything, as noted, but I guess I was looking for some common area ,other then ECM, that might be causing the no start because the ECM testing seem to check out ok. I wanted to get a new chip made to bypass the vats on the car so I called PMC of NC for info. I filled out the file and emailed it in to them .On the file there was a line that ask for the chip id , number of letters so I pulled the chip and noted the numbers, took a picture, put the chip back in and about then my problem started .So last night ,checking everything that I could think of, I pulled the screws out of the ECM and checked the chip because I read somewhere that it could be put in backwards. It wasn't in backwards but it wasn't seated completely .Took it out, looked it over and reinstalled it and wa-la . I hope this was the main/only issue with the no-start problem and I like to thank everyone for your help. I still have two months to get this car ready and I am sure it has other issues .So for this weekend I will re-pull the distributor and move it ahead one tooth ,see why the low oil light is on with lots of oil in engine and pressure gauge good , start on the Bose radio removal/change out while waiting for my chip and headers to come, maybe start installing some interior parts back together.
cheers everyone.

 

did you move the dizzy by one tooth? i missed it if you did.

 

not yet

 

Not yet. Got side tracked by a crack in the water pump.