Frustrated w-fuel delivery issue! Help!

[sponge]

Hi guys,

I have been trying to get fuel to my engine all day wo any success

My engine:
AMC 258 i6 / 4.2l block
97 ZJ head and intake
92 XJ ECU and EFI

We have done the following to get it running

- dropped the tank and put the fuel lines into a 5 gallon gas can
- started from the front to the back to troubleshoot
- replaced the fuel pump still no dice
- blew out the lines with the air compressor
- replaced the fuel filter

The pump primes but is not pulling fuel out to the engine.

We are at a loss and defeated...only thing I can think of is the ecu may not be happy and once the pump primes it isn't send the signal to pump?

I will be VERY grateful for any help...ready to call the local shop
-

 

[jasonmark1993]

Some ECUs will prime the pump with the initial key on cycle, then it will stop until you crank or get the engine running.

The initial prime is enough to get the fuel pressure up; but that's once you've got it primed.

You're positive that the return/pressure lines are on correctly?

Are you using the factory type click fuel connections or something different? I would look at somewhere where the pump is able to pull air instead of getting a good suction. You may need to get the pump below the fuel for a second. Maybe try raising the bucket up above the pump.

Hows the pump mounted? Is it in the tank or external?

 

[IOPort51]

If you have an external tank put a meter on the terminals or the fuel pump relay and check for power after prime.

 

[jasonmark1993]

We might need more info.

If you are just turning the key on you'll only get a few seconds of prime without the engine running/cranking. Once you start cranking it'll power the fuel pump relay again.

Is that what is happening?

Just cycle the key a bunch of times. I'm guessing from what you said the pump is running but just for a few seconds. Thats normal.

 

[Old Dog]

Does I fire at all?
My Howell system acted like this once, the ICM was bad and the pump would not run without getting spark.

 

[sponge]

You're positive that the return/pressure lines are on correctly?

Are you using the factory type click fuel connections or something different? I would look at somewhere where the pump is able to pull air instead of getting a good suction. You may need to get the pump below the fuel for a second. Maybe try raising the bucket up above the pump.

Hows the pump mounted? Is it in the tank or external?

I am using the factory style clip at the intake of. The fuel line

The pump is mounted externally on the rear crossmember the tank hangs on

I thought of the idea to raise the tank but was quickly talked out of that due to the pump should be strong enough but ith completely empty lines it makes sense

 

[Purple77CJ7]

I had issues with my Howell TBI. The electric pump would not prime. I had to put a jumper wire in the fuel pump relay, so I could make it run as long as I wanted, more than just initial key on. Being able to run it that way I got it primed. It was easyer to do that than run a wire from the battery down to the pump. Just a thought.

 

[sponge]

If you have an external tank put a meter on the terminals or the fuel pump relay and check for power after prime.

Agreed and on the agenda, I need a meter?...if that the case then I will do the by pass suggested above.

The frustrating part is I had no issues with the previous OEM tank

Thank you everyone...

 

[Torxhead]

If you think you might have a problem with the fuel tank, it should be able to siphon gas out on its own prior to the fuel pump with the gas cap is removed.

 

[IOPort51]

I also had no problem with the OEM tank except it was full of stuff. cleaned it out and put it in the barn. thought the poly tank would be good for the ethanol issue now I am not so sure. Major PITA.

Agreed and on the agenda, I need a meter?...if that the case then I will do the by pass suggested above.

The frustrating part is I had no issues with the previous OEM tank

Thank you everyone...

 

[jasonmark1993]

Well if your pump is running you don't really need a meter.

Its possible it isn't getting full power but that is very unlikely.

Can you tell us when the pump runs and for how long?

I've never run a high pressure pump externally like you are. It is possible that this is simply a problem of getting the pump primed.

 

[IOPort51]

of course you need a meter, every body should have a meter. Not only will it tell you if it is running but the amperage reading will tell you if it is actually moving liquid.

from where you are right now I would pull the fuel line down stream from the pump and jump the relay to be sure you were primed. but only because you don't have a meter.

Agreed and on the agenda, I need a meter?...if that the case then I will do the by pass suggested above.

The frustrating part is I had no issues with the previous OEM tank

Thank you everyone...

 

[sponge]

I can hear the pump prime, but it isn't pulling fuel past the fuel filter...I put on a new filter thinking it was clogged no luck, then replaced the pump and no luck.

I have really convinced myself that it is priming but needs to continue to pump to fill the lines and the computer isn't allowing it...so hardwiring the pump to see if that solves the issue may be the way to go.

The hard part in all this is the Jeep is at my dads 2 hrs away, so over 2 weekends I have spent 6 hours driving, $100 in gas, and $200 in parts that were not needed...

My dad has a good shop that works on his old vette I am thinking I can have them tow it over to their place to troubleshoot and get running before I waste more time and money over something that is probably simple but beyond the time I have...and probably save me money too.

It is so close I can feel it!

 

[jasonmark1993]

If that is the situation you should just be able to cycle the key repeatedly and it'll get there.

The pump may be turning off before fuel actually gets to the pump so that when it shuts off what fuel it was starting to pull runs back to the tank.

You may need to crank so the pump has a little longer to run; or just jumper it like you said. If you do that I'd recommend unplugging the pump from the harness.