Truck turns over, fuel pump newly replaced and cuts on, no fuel being moved at all

[danielhood187]

Just replaced fuel pump in a 1989 Jeep Comanche and it won’t start we hook it up to an f-250 to help start it and it’s perfect the new fuel pump turns on and all but does not send fuel anywhere all fuel line have been cleaned but the vacuum system is done for because of a small fire will the vacuum line have something to do with this?

[jdog]

If the fuel is not getting to the rails its a fuel line or pump issue. The vacuum system doesn't have any say as to the pump running or not. I'm assuming it is a 4.0 l

 

[EUREKA]

When you say,

Quote

we hook it up to an f-250 to help start it and it’s perfect

what exactly is it that you are hooking up to the f-250? Are you jump starting the jeep?

How are you detecting that the new pump runs, sound?

With the fuel line off of the rail, the pump does not pump fuel when on?

[MiNi Beast]

Check fuel pump before fuel filter to ensure pump working. Check fuel after inline filter to ensure it's not clogged, next place be fuel rail then spark plugs for fuel. 

 

[danielhood187]

The fuel pump it’s running it’s brand new. I heard when I put my ear up to the tank and have someone turn it on but it doesn’t move gas at all entire fuel system is dry but there’s a half tank of gas in it and the fuel lines blew out and new filters but it hasn’t ran it 10 years and sat in a barn.

[danielhood187]

Yes 4.0 it’s a 1989 Jeep Comanche pioneer 2x4 4.0i automatic trans

[danielhood187]

On 1/16/2022 at 1:22 PM, EUREKA said:

When you say,

what exactly is it that you are hooking up to the f-250? Are you jump starting the jeep?

How are you detecting that the new pump runs, sound?

With the fuel line off of the rail, the pump does not pump fuel when on?

Yes Jump starting it it 

[danielhood187]

Going off of sound 

[EUREKA]

2 hours ago, danielhood187 said:

The fuel pump it’s running it’s brand new. I heard when I put my ear up to the tank and have someone turn it on but it doesn’t move gas at all entire fuel system is dry but there’s a half tank of gas in it and the fuel lines blew out and new filters but it hasn’t ran it 10 years and sat in a barn.

Regardless of what you hear, or which parts are new, I would listen to MiNi Beast. I'm sure he meant to write "test spark plugs for spark".

A common troubleshooting path is to test for spark, then fuel delivery, then compression, then things like timing if necessary. In this case it is fine to test for fuel delivery first. Personally I would recommend a fuel pressure gauge. I use this one, Fuel PSI gauge .

 

Is the gas 10 years old? This isn't a zombie movie ya know.

[gogmorgo]

So taking you at your word you've got a running fuel pump and new filter, but no fuel pressure at the rail.

Firstly we'll ignore the vacuum harness situation in terms of fuel delivery. Depending on what happened and where it could be causing other problems that will give you running problems, but it won't stop fuel from reaching the rail. Having no vacuum line on the fuel pressure regulator is the same as having low vacuum, essentially wide open throttle at full load, so you'll get full fuel pressure. Not a concern.

Your new fuel filter will have an arrow on it indicating flow direction. Many of them have a check valve, so if you put the filter on backwards you won't get fuel through it. We've all done it, which is why I bring it up, nothing against you personally.

It's VERY possible that the rubber line between the fuel pump and sending unit has failed. If you reused the old hose, its almost guaranteed it didn't survive the R&R process. If you used a new chunk of hose that isn't submersible, it's also unlikely it's going to last very long. Most replacement fuel pumps aren't the same fit as the original and come with an adapter kit, and some are much better than others. I've personally seen them come apart in a way that makes you run out of fuel at just under a 1/2 tank. If you used a full MTS sending unit, hypothetically none of these are a concern, in which case you have a pump that should be pushing fuel out to the rail, but isn't. If the pump is running, either it's not sucking up fuel, or else something is obstructing the fuel flow, or diverting it out of the line somewhere. Your next step will be to figure out where fuel is flowing and where it's not, and what's going on between those two points to stop it from happening.

[danielhood187]

11 hours ago, EUREKA said:

Regardless of what you hear, or which parts are new, I would listen to MiNi Beast. I'm sure he meant to write "test spark plugs for spark".

A common troubleshooting path is to test for spark, then fuel delivery, then compression, then things like timing if necessary. In this case it is fine to test for fuel delivery first. Personally I would recommend a fuel pressure gauge. I use this one, Fuel PSI gauge .

 

Is the gas 10 years old? This isn't a zombie movie ya know.

No I dropped the tank and cleaned the whole fuel system and I hook a syringe to the fuel rail and got it started literally everything wooks on the jeep except for the fuel system . Iv been resorting it but the last thing is the fuel but I in hook the fuel Lines and the pump turns on just move no gas

[jdog]

Then it's either a bad pump, bad hose or incorrectly installed lines to or at the filter. It could also be wired in reverse and Sucking from the wrong side of the pump

I always say just because it's new doesn't mean it's good

[Eagle]

16 hours ago, danielhood187 said:

The fuel pump it’s running it’s brand new. I heard when I put my ear up to the tank and have someone turn it on but it doesn’t move gas at all entire fuel system is dry but there’s a half tank of gas in it and the fuel lines blew out and new filters but it hasn’t ran it 10 years and sat in a barn.

 

Sat for ten years?

 

When you installed the fuel pump, did you install a new "sock" for the fuel pickup in the tank? Ten years worth of varnished fuel accumulation might have made the sock basically impervious.

[danielhood187]

19 hours ago, gogmorgo said:

So taking you at your word you've got a running fuel pump and new filter, but no fuel pressure at the rail.

Firstly we'll ignore the vacuum harness situation in terms of fuel delivery. Depending on what happened and where it could be causing other problems that will give you running problems, but it won't stop fuel from reaching the rail. Having no vacuum line on the fuel pressure regulator is the same as having low vacuum, essentially wide open throttle at full load, so you'll get full fuel pressure. Not a concern.

Your new fuel filter will have an arrow on it indicating flow direction. Many of them have a check valve, so if you put the filter on backwards you won't get fuel through it. We've all done it, which is why I bring it up, nothing against you personally.

It's VERY possible that the rubber line between the fuel pump and sending unit has failed. If you reused the old hose, its almost guaranteed it didn't survive the R&R process. If you used a new chunk of hose that isn't submersible, it's also unlikely it's going to last very long. Most replacement fuel pumps aren't the same fit as the original and come with an adapter kit, and some are much better than others. I've personally seen them come apart in a way that makes you run out of fuel at just under a 1/2 tank. If you used a full MTS sending unit, hypothetically none of these are a concern, in which case you have a pump that should be pushing fuel out to the rail, but isn't. If the pump is running, either it's not sucking up fuel, or else something is obstructing the fuel flow, or diverting it out of the line somewhere. Your next step will be to figure out where fuel is flowing and where it's not, and what's going on between those two points to stop it from happening.

This was extremely helpful I’m going to try some things tomorrow and let you know what happens 

[MiNi Beast]

Swap wires on fuel pump and presto. 

[jeepmjga]

Maybe ballast resistor is unplugged? Should be a ceramic resistor with two terminals on the drivers side top inner fender. 

[EUREKA]

35 minutes ago, jeepmjga said:

Maybe ballast resistor is unplugged? Should be a ceramic resistor with two terminals on the drivers side top inner fender. 

Maybe, but it should still start and then immediately die once the key is returned to "RUN"  because the pump is powered via the starter relay while cranking, then ECU powers it via the ballast resistor circuit (I believe, I newish to renix). That's how mine acts with the wire unplugged at the ballast resistor.

 

Best to troubleshoot rather than guess imo. Must begin with verifying no fuel pressure at the line before the filter.
IF there is fuel pressure before the filter:

  verify filter is installed correctly. IF filter is installed correctly, move to the rail/injectors.

   if pressure is present at the rail, troubleshoot injectors/injector wiring.

 

IF there is not fuel pressure in the line before the filter:

 verify battery voltage at the pump. If not present troubleshoot electrical issue.

 If there is battery voltage, remove the pump and look to the sock or other pump components.

[MiNi Beast]

12 minutes ago, EUREKA said:

Maybe, but it should still start and then immediately die once the key is returned to "RUN"  because the pump is powered via the starter relay while cranking, then ECU powers it via the ballast resistor circuit (I believe, I newish to renix). That's how mine acts with the wire unplugged at the ballast resistor.

 

Best to troubleshoot rather than guess imo. Must begin with verifying no fuel pressure at the line before the filter.
IF there is fuel pressure before the filter:

  verify filter is installed correctly. IF filter is installed correctly, move to the rail/injectors.

   if pressure is present at the rail, troubleshoot injectors/injector wiring.

 

IF there is not fuel pressure in the line before the filter:

 verify battery voltage at the pump. If not present troubleshoot electrical issue.

 If there is battery voltage, remove the pump and look to the sock or other pump components.