• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Help! Need Troubleshooting Advice

J

JstSurrender

NAXJA Forum User
Location
Salem, Or
First off, I've got an '88 Cherokee Pioneer. Basically stock. I replaced the fuel pump just a couple hours ago. When all was said and done I tried to start it. It just sat there turning over. I was going to disconnect the fuel line to ensure the pump is indeed pumping fuel to the engine but I'm not exactly sure on how to do that.

Also, the Jeep has been running pretty unstable lately, running weak having trouble running unless I gave it gas. Noise(humming) coming from the back of the Jeep right above the fuel tank, and running inconsistant while driving let me to believe fuel pump. Just the other night when I replaced the fuel filter(because I knew it had never been replaced) a friend of mine noticed arching from the top of the boot on a spark plug.

Guys I really need this thing running, I could use so much help right now...
 
JstSurrender said:
Yes sir, turn the key, listen to it prime, then try and start it and it just sits there turning over. Just won't start.
Click to expand...
You will need to check for fuel pressure on the rail then. There is a test port near the pressure regulator.
 
You need fuel in the appropriate amount and spark at the appropriate time. If your ingine is fuel injected, check fuel pressure with a gauge, using the fuel rail shrader valve. Your motor manual for your particular engine will give you the specs. For spark, pull a plug wire and hold the exposed metal end approximately 1/4 inch from the engine block/head while some one trys to start the engine. You should see the spark jump the gap. These are the easy first two steps that should tell you what to trouble shoot first.
 
Ok, so I've got no fuel pressure at all. I disconnected both lines coming out of the fuel pump(first one going to the fuel filter) to see if any fuel was being pumped out and there wasn't anything.

When I turn the key, I can hear the pump priming, but I don't see any fuel coming through during the priming or when I'm trying to start the engine.

I'm positive i've got the wires connected properly, and the tubes. The pump is in place in the tank, I removed the tank last night to put the pump back in.

Next steps? I don't really want to pull the tank down again, as I'm by myself now...but that's what jacks are for right? (man this sucks lol)
 
If the pump is running but no gas is coming out, the short fuel line hose that connects the pump to the mounting bracket may have come loose. I have also seen people get the wires swapped on the pumps. Some after market pumps I have seen actually have the terminals reversed from the OEM pump.
 
JstSurrender said:
Ok, so I've got no fuel pressure at all. I disconnected both lines coming out of the fuel pump(first one going to the fuel filter) to see if any fuel was being pumped out and there wasn't anything.

When I turn the key, I can hear the pump priming, but I don't see any fuel coming through during the priming or when I'm trying to start the engine.

I'm positive i've got the wires connected properly, and the tubes. The pump is in place in the tank, I removed the tank last night to put the pump back in.

Next steps? I don't really want to pull the tank down again, as I'm by myself now...but that's what jacks are for right? (man this sucks lol)
Click to expand...
I changed mine without a jack or dropping the tank, took about 20 min's and a beer.
 
old_man said:
If the pump is running but no gas is coming out, the short fuel line hose that connects the pump to the mounting bracket may have come loose. I have also seen people get the wires swapped on the pumps. Some after market pumps I have seen actually have the terminals reversed from the OEM pump.
Click to expand...

I took the tank down, no problems there. I looked at the pump and it's connected correctly as far as tubes go. I guess I'll switch the positive and negitive to see if that chagnes anything. Think I can leave the tank down just connect the electrical part of the pump, turn the key and see if it pumps?
 
JstSurrender said:
I took the tank down, no problems there. I looked at the pump and it's connected correctly as far as tubes go. I guess I'll switch the positive and negitive to see if that chagnes anything. Think I can leave the tank down just connect the electrical part of the pump, turn the key and see if it pumps?
Click to expand...
Yes just be carefull of sparks.
 
Ok, so I connected the pump after switching the pos. and neg. I still didn't get anything. Any other suggestions on how to test that this pump is actually working? I can hear it but I don't see it producing anything...the tank is obviously not pressurized at this point but with the pump grabing gas from the bottom of the tank I don't see that being a problem.

Maybe defective pump? It's a bosch from Napa...

~Scott
 
Yes, i replaced my fuel pump with a unit from autozone. Sure nuff the terminals were reversed from oem, the darn thing was running backwards. Quick way to check is fuel rail pressure. Also check the little rubber line on the pump, it sometimes will come off if only partially especialy if it's old.
 
Well, after switching the terminals and testing it to see if it would pump anything I've decided to head over and swap if for another...not sure what else to do...
 
alright, to continue my need for troubleshooting advice, I'm still working on my Jeep. Problem is that it dies right after you start it. I can't keep it idling. In order to keep in running I need to press the gas. Once on I'm on the road and it gets warm I can drive around fairly confident, however it seems to run weak. I've currently replaced fuel pump, plugs, wires, rotor, cap, MAP, Fuel filter, and I've cleaned the IAC. I'm wondering if there is a way to test the IAC to be sure that it's working. I've tested the TPS and that seems to be working fine. THis is my DD so I need it running ASAP. Thanks for you help guys.

~Scott
 
You must log in or register to reply here.

Similar threads

R
Fuel Gauge Troubleshooting
2
Replies
26
Views
4K
Rob Mayercik
R
Z
RENIX fuel delivery questions
Replies
4
Views
331
Ecomike
Ecomike
J
Cranks, Fires, Dies - 1991 Briarwood Restoration
Replies
17
Views
3K
Jam Master Jay
J
N
New Engine is Hard to Start
Replies
0
Views
33
NGThomas
N
V
High temp woes
2
Replies
21
Views
399
Vitzaa
V
Back
Top