Fuel Pressure Issue

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CERES2

CERES2

10 Year 15 Year
Joined
Apr 4, 2009
Threads
27
Messages
99
Location
Tucson , Arizona
Good Morning. I have been struggling with a fuel issue for the past 10 months or so. Every time I take the Cruiser out in the desert it begins hesitating and stalling 50 miles or so into the trip. It goes away for a little while when I let it sit. I have checked several threads and followed up on recommendations: (1) cleaned fuel filters and fuel tank. (2) replaced broken VCV valve and checked the charcoal canister. So far no success.

Today I followed the repair manual's instructions for a fuel pump check perhaps hoping that a bad fuel pump may be the cause: I connected terminals B and FP, turned the ignition on and expected to see fuel flow from the return hose but nothing came out!. I left the return hose off (feeding into a gas can) and started the cruiser without a problem. Still no gas from the return line!

According to the manual, the fuel pressure regulator may be busted. Question is: would that cause the symptoms described above. Anybody ever had this happen?

Thanks!
 
You say, "cleaned fuel filters".
How do you do that when the inline fule filter is a sealed unit?

Did you replace the inline fuel filter on the right frame rail under the distributor?
Did you replace the pre-filter on the fuel pump?

What you are describing are the EXACT symptoms of a clogged pre-filter.
 
Yes. I forgot to mention that I replaced the EFI relay (under the hood left of engine). Also replaced (rather than cleaned) both fuel filters and cleaned out the tank (drained and flushed).

The symptoms are very disturbing. Severe hesitation getting worse by the mile. Engine idles perfect but any load will make it lurch and hesitate. Full throttle depression makes it worse. Letting it sit overnight will make it go away for another 50 miles or so (luring me back into the desert only to limp home once again).

Help!!
 
So basically the truck runs great for the first hour, then it goes south.
Sounds like it's starving for fuel. If this was EFI related, throttle position wouldn't really effect it too much. Fuel pressure may be way off due to partial vacuum in tank if the return line is clogged or the FPR could be toast. If it's the original it might be worth replacing for PM in any case. The FSM has a test for the charcoal canister as well.
 
Thanks, I'm calling Dan for an FPR first thing tomorrow.

Could it have anything to do with the EGR Modulator or Vacuum Switch Valve?
 
Working on the vacuum in the tank idea, have you tried to remove the gas cap when this happens to see if it makes a difference?
 
I dont know if this helps, but I just had a fuel pressure issue. I had fuel pressure in the return line and could hear the pump running so I checked all the other things like filters, vsv, etc. Turned out to be the fuel pump after all. It was just weak. It caused the truck to run bad. Replaced pump and the truck runs great. It may be that your pump is getting hot after an hour and pressure is dropping off. I would suggest getting a pressure gauge because if I had one it would have saved me a lot of time. Just my 2 cents.
 
CERES2 said:
Thanks, I'm calling Dan for an FPR first thing tomorrow.

Could it have anything to do with the EGR Modulator or Vacuum Switch Valve?
Click to expand...

Typically, failed EGR shows itself as poor power below 2100 RPM and a "turbo boost" feeling above that. It also would be more consistant rather than working well for an hour and then going south.
 
Wife's 92 just did the same thing. After about an hour into a trip it started missing. I'm hoping it's the EFI relay (because I have a new one in the glove box). I just got her to change it and am hoping it will fix the problem. I will know tomorrow evening when she starts back. (New fuel filter 2 weeks ago and new fuel pump 9 months ago.)

CERES2 let me know if the FPR fixes yours, I would appreciate it.
 
SUMMIT: New FPR came in yesterday. Replacing it this weekend. It may be a week or so before I get the Cruiser out on a trail to test. I'm keeping my fingers crossed.
 
CERES2 said:
SUMMIT: New FPR came in yesterday. Replacing it this weekend. It may be a week or so before I get the Cruiser out on a trail to test. I'm keeping my fingers crossed.
Click to expand...

Ceres2, I think I'll order a new one also. Mine's original with 305K. I think it's time.
 
Ceres2,
Update, truck made it home with new EFI relay. Outside temps were about 15 degrees cooler (70 degrees). I checked the EFI relay and it was extremely hot. This weekend I will be working on upgrading the EFI wiring to 10 gauge and relocating it to the inside cab. I did order the FPR from Dan hoping one of the two will fix my problem as well.
 
SUMMIT CRUISERS said:
Ceres2,
I checked the EFI relay and it was extremely hot. This weekend I will be working on upgrading the EFI wiring to 10 gauge and relocating it to the inside cab.
Click to expand...

I have to do this as well, although I've never checked it. Isn't this the wiring that 3FE owners around here recommend upgrading, or is that something else? Remember to snap a few photos, It will make my job easier. Both my FPR and EFI are original, 304,000 miles on them, thinks it time for Dr. Kavorkian.
 
Tenzig Norgay said:
I have to do this as well, although I've never checked it. Isn't this the wiring that 3FE owners around here recommend upgrading, or is that something else? Remember to snap a few photos, It will make my job easier. Both my FPR and EFI are original, 304,000 miles on them, thinks it time for Dr. Kavorkian.
Click to expand...

EFI Relay Pics 4 U
 
Update: I replaced the FPR but still no fuel coming through the return line. So I'm more leaning towards a crappy fuel pump now. pretty soon I will have replaced every fuel related component electric or mechanical. :)

I also replaced the old EGR modulator which had a broken connector. The filter was chock full of carbon. While messing with the vaccum lines I noticed that some of the metal tubes are blocked. Does anyone have a clever way to clean these out. I tried compressed air and electrical wire. No luck.
 
Update RE: 92 FJ80
I relocated the EFI relay to inside the truck last weekend with (2) 10 gauge wires and (2) 14 gauge wires. Relay is hot but not as hot. I then replaced the fuel pressure regulator (fpr) last night. Today my wife tested it out and drove to Tulsa and about an hour out and it started sputtering again. I had her replace the EFI relay with a new one. That helped for about 10 minutes. I had her check the relay again and it was warm not hot.
Conclusions, not sure what the problem is. Relocating the EFI relay inside the cab with bigger wire helped its temperature out but did nothing to fix the problem. Any more ideas before I ditch the 80 and buy a Jeep Cherokee or Liberty? Just kidding on the Jeep idea. :bang: HELP PLEASE!
 
Have you checked you fuel pump and made sure it's flowing correctly and building pressure? Your not going to get any fuel into the return line until your fuel pump has met the correct pressure. If it's not making enough psi's the regulator isn't going to open.
 
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