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454 tbi no fuel question

79BRUISER

79BRUISER

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I have an 88 c&c k30 with a 454 tbi. I can get it to run using starting fluid, but the fuel pump won't kick in.
I checked the fuel pump and will run with 12 volts jumpered to it.. I even checked the other fuel pump and it works also. I swapped the fuel pump relays and still nothing. I checked the tank selector switch and its working.
I found that the ground on the tps connector pin was broken. I rigged that into the tps plug. I haven't checked for the 5 volts from the reference wire yet. Could the tps keep it from firing the fuel pump?

I looked over all the other connectors i could find and they look ok.

I have no experience with TBI. My electrical manual has come up
missing.

What else am I missing that could keep the fuel pump and injectors from firing?

Thanks for the help.
Bruiser
 
Did you check the ECM fuses, mine did that once and it was a 15 amp fuse.
Tarey
 
Have you verified the relay actually works? When you turn the key on, there should be +12v (sent to the fuel pump) for about 2 seconds on the brown\white wire coming out of the relay.

If the relay is good, check the connection to the ECM. If that's good, then I've been told to check the ignition module since the ECM will only turn the fuel on if it sees ignition response.
 
Your oil pressure switch is redundant to the pump relays, relays shouldn't matter, and unlikely two relays are dead along with the oil pressure switch.

With the pump jumpered to 12V, will it actually start and run? If it won't, your injectors aren't firing, which means ignition more than likely.
 
dyeager535 said:
Your oil pressure switch is redundant to the pump relays, relays shouldn't matter, and unlikely two relays are dead along with the oil pressure switch.

With the pump jumpered to 12V, will it actually start and run? If it won't, your injectors aren't firing, which means ignition more than likely.
Click to expand...

It won't run with the fuel pump jumpered.

The injectors aren't firing. I checked for voltage while cranking the engine.

So where do I look now?
 
if the vehicle is new to you and never run before check that you have a 12v source to the alternator from the battery or the junction block. it sounds like something that happened to me. i switched out stoc batt cables for thicker ones and forgot about the lead to the alternator when putting in the new ones. check to see if there is power to your ecm fuses.
 
How did you test voltage? Key in run, one of the two injector wires should have constant 12V. Do NOT use the other wire as the ground for the test gauge/light, as the ECM switches that line to ground.

If you have no voltage at the injectors with the key in run, something is wrong with the power feed to them, which is either a wire or fuse.
 
Ok, I followed all your advice and there is 12v at alt. There is 12 volts at the ecm1 and ecmb and ignition fuse. There is 12 volts at the injectors. Checked injector wires to ground and got 12v on all 4.

I did blow the ecmb fuse, I suspect by the way I checked the injectors the first time. I checked it to ground this time.

Still nothing.

So the injectors are trying to fire, but something is keeping the fuel pump from kicking in????

Wish I could find my wiring schematic.

Thanks for the help, Bruiser
 
Have you checked the fuel pump fuse near the relay?

Edit: since you jumped it and it runs, it seems to be ok.

I'd still check that the relay is getting 12V on the signal wire when the key first turns on. That will tell you if the ECM is trying to do its job. I'd also make sure the fuel pump oil pressure switch is hooked up to help eliminate the relay as a problem.
 
bp71k5 said:
Have you checked the fuel pump fuse near the relay?

Edit: since you jumped it and it runs, it seems to be ok.

I'd still check that the relay is getting 12V on the signal wire when the key first turns on. That will tell you if the ECM is trying to do its job. I'd also make sure the fuel pump oil pressure switch is hooked up to help eliminate the relay as a problem.
Click to expand...

I looked again, and don't see a fuse by the relays.
 
I jumpered the fuel pump at the fuel pump. What does the oil pressure/ fuel pump sensor look like. Where is it? The print I have from autozone shows gray and orange wires. Does that sound right?
 
oil pressure sensor wires right color. possible location front of intake manifold, by oil filter, or on bottom front driverside side of block.
 
The oil pressure sensor on mine was near the back side of the distributer at the oil pressure gauge sender.

I jumpered the fuel pump at the fuel pump.
Click to expand...

You want to give 12v to the red pigtail attached to the fuel pump relay to jump the fuel pump.

It does seem unlikely that two relays would be bad, but I'd at least eliminate it as a problem. Check the green\white wire going into the relay to see if it gets 12V for the first 2 seconds after turning the key on. Then with the key on, check the fat orange wire to see if it has 12V constant. Those two bits of info will tell you whether the problem is the relay or whether it's further up in the system.

don't see a fuse by the relays.
Click to expand...

Sorry, I added one to mine since it was a conversion. Stock fuses appear to be in the fuseblock and are just the ECM fuses.
 
12V to the injectors does NOT mean it's trying to fire. That is the "normal" state of the circuit. The ECM grounds the injector lead when it "sees" that the engine is turning over via the ignition module.

You need to put an analog (not digital!) voltmeter, or a 12V trouble/noid light on one of the injector connectors, this time between both wires on the connector. Then crank the engine. If the light does not blink, then the ECM is NOT firing the injectors.

I think you are way off track looking at relays/oil pressure switch if you have already determined the truck will not start with the fuel pump wired to 12V. Maybe the fuel pump itself, but the relays/switch have NOTHING to do with a no-start condition if the pump runs when it is given 12V from the battery.
 
check for injecter pulse u need to geta pulse injecter checker it plugs into the wiring that normally goes to the injecter and it has a bulb if the light doesent blink then you arnt getting pulse.also check if your distributer if its bad if it is then u wont get fuel to the injectors and check the ignition module auto zone can test it
 
the relays/switch have NOTHING to do with a no-start condition if the pump runs when it is given 12V from the battery.
Click to expand...

This is more of an acedemic question, and I understand they don't affect the condition directly, but wouldn't determining that the problem is before or after the relay isolate the problem to the ECM or ignition?

I don't disagree that the problem is likely in the ignition, but one good way to troubleshoot stuff like this is to work backwards from where the problem is.

Since we know the fuel pump itself works, checking the item that supplies power to the pump takes no longer than 2 minutes and it isolates the problem to somewhere upstream of the relay. Doing it that way eliminates all the potential broken wires, unplugged connectors, blown fuse possibilities and narrows the problem down to one particular system.

I suppose after you determine the relay is good, and that it's just not getting a signal, the next logical item to check is the ignition module or ECM so I may just be suggesting a longer road to the same conclusion.
 
IMO it's a lot easier to fix the known, serious issue, than to try and fix other issues that may or may not be related, and which may or may not be solved when the root issue is taken care of.

If I was confident that the fuel pump has been tested properly, I might then think fuel delivery issues to be worth trying to fix...as it is now, do we KNOW that the fuel pump does not run when everything is hooked up correctly and the engine is cranking?

I suppose an easier way to say this, is that more thorough testing needs done, instead of bouncing around from component to component. :)
 
:whistle: Distributor module or pickup coil.

Anytime i have a no start no fuel problem.First thing Icheck is the module.
Just takes a few minutes to throw in a spare. Dont have a spare? You should have. While replacing the module put an ohm meter between the pickup coil leads. Should be 500 to 1500 ohms.
 
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