Question about 1990 Jeep Wrangler

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With the key turned on and the engine off, the fuel pump stays on. Can this be caused by a faulty fuel pressure regulator, or possibly a leak somewhere in the fuel line? Where should I start in diagnosing the problem?

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Its a bad fuel pump relay. replace it with another relay. you can also take or like fog light relay and replace it with that or replace it with something less important like horn relay.

Posted on Dec 02, 2012

Testimonial: "Thank you for your response! It is greatly appreciated!! Today when I went out to start it, it wouldn't start. If I let it sit for a second and let the fuel pump build up pressure, it feels like it wants to start but doesn't. If I prime the carb it starts fine, and continues to run. I think the fuel pump is bad, unless you think this problem can also be caused by a faulty relay."

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Posted on Jan 02, 2017

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SOURCE: 1993 Jeep Grand Cherokee Fuel Pump?

Between 100-140 thousand miles the fuel pumps go out on the 1993 cherokee. Its a fact. All parts are manufactured with the knowledge that it will last for a specific period of time then it dies. The relay switch was helpful for a brief while because there was still some juice in that pump, but now that it is gone it is gone.

If you don't see the fuse box under the dash in the driver leg area or beneath the radio check for a covered box under the hood. There should be a fuse spec guide on the lid of the box that tells you where specific wattage should go and for what purpose. But, your fuel pump problem will not be solved by a new fuse.

Posted on May 25, 2009

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SOURCE: 1999 Jeep Grand Cherokee Died while driving home

check the fuel pump fuse/relay, could be just bad enough to cause an intermittent start/no start. and check fuel pressure,spark and the crank position sensor.

Posted on May 27, 2009

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SOURCE: Starting Problem with 1994 Jeep Grand Cherokee

Assuming I understand your problem correctly, it sounds as if the car will only start once the check engine light comes on.  The check engine light is controlled by the PCM (powertrain control module; or computer) which is also responsible for basically all engine operations including fuel delivery, ignition, emissions, and so on.  If this light is not coming on, it means that the computer is not getting power.  If the computer is not getting power then it won't start.  The fact that you hear the relays click on when the light comes on is another indicator the the computer is not getting power as it also supplies power to the ASD (Automatic Shutdown Relay) which in turn supplies the power to the fuel and ignition systems.  Check the ASD relay located in the power distribution center, if it is the same relay number as another un-important system, then swap it out to see if that helps.  Make sure the plugs going into the computer are tight.  The delay in the power going to the PCM sounds like a stuck relay, have someone tap the relays when the light is off to see if comes on.  It is also possible that the PCM itself is failing.

Posted on Dec 16, 2008

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SOURCE: 2000 Jeep Grand cherokee Laredo

sounds alot the the pcm it controls the fuel pump and ign system but the anti theft would keep it from starting because the key has a transponder in it programmed for that vehicle and that would kill all ign if triggered

Posted on Sep 27, 2009

  • 49 Answers

SOURCE: new pump, no fuel pressure at fuel rail??

fuel pump relay

Posted on Oct 04, 2009

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I have a 01 chevy blazer with a 4.3 vortec engine I want to no if a faulty fuel injector spider would cause low fuel pressure


low fuel pressure is from
bad pump,
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faulty pressure regulator
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My fuel pressure goes to 60 pounds when the keys is turned on then starts dropping Is it my fuel pump or pressure regulator? 2004 GMC Yukon XL


Fuel pressure may drop due to a leaking injector or bad check valve in the fuel pump itself. The regulator does not come into effect until the engine is running and a vacuum supply is produced to it. If the regulator is leaking internally, it could send fuel back to the tank as well. Prime the fuel line and pinch off the return line ( if possible ) to eliminate a regulator problem. If the fuel pressure drops with the return line pinched off, suspect a leaking injector or fuel pump. If injector is leaking, the vehicle should run rich and cause a hard start/rough run condition

Jul 25, 2015 | 2004 GMC Yukon XL

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97 s10 4.3 vortec..flooding when engine is hot. Went from 24 mpg to 13. Changed fuel pressure regulator. egr valve.Plugs,wires,cap and rotor button. Fuel pressure stays between 55 and 61 at all speeds,...


The fact the fuel pressure does not hold after the pump stops is a big problem indicating a fuel leak into the upper manifold, which would cause the flooding. This leak could have several causes, but since the problem is still there after replacing the regulator, it sounds like the problem is with the injector in the spider assembly.
It sounds like you have a design 1 spider assembly, with only one fuel injector distributing fuel to the six poppets. If that is the case, I suggest you try replacing the entire assembly (which will include a new regulator) with the Delco design 2 version which has injectors on each poppet.

May 28, 2017 | Cars & Trucks

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WHY DO I HAVE TO POUR WATER ON MY FUEL RAIL AFTER IT IS HOT SO THE ENGINE WILL START


Hi James,

That is a real good question. Have you checked the fuel pressure on the fuel rail to see how much pressure there is when it refuses to start? It sounds like you may be losing your fuel pressure because of the fuel returning to the tank when the engine is hot. This could be due to a faulty fuel pump assembly or a faulty fuel pressure regulator.

Try this: When it doesn't start, turn the key OFF and wait about 15 seconds, then turn it back to the ON position (do not try to start yet). Repeat this a second time, only this time turn the switch to the START position. If the engine starts, then it is definitle due to loss of fuel pressure in the fuel rail. You will then need to test your fuel pressure with a gauge and plug off the return line to determine if the problem is being caused by the regulator or the pump.

Oct 16, 2011 | 1995 Pontiac Grand Am

1 Answer

1993 Chevy K-1500 5.7 L TBI Starts normally when cold - Difficulty starting hot - Have to hold accelorator to floor to start - Takes 2-3 mins. at approx 1/3 throttle (with much smoke) and everything is...


This is almost certainly caused by a lack of fuel pressure . The fuel pressure will be fine while the engine is running but when it is switch off the pressure won't hold . In the trade we call this residual pressure . What happens when this fault occurs is that the fuel in the engine fuel rail will vaporize and hence the hard starting .

There are three possibilities : leaking injectors , a faulty pressure regulator valve or a faulty check valve in the fuel pump .

First thing to do is to check the fuel pressure while the engine is running and then switch the engine off , if the pressure drops drastically over a period of 20minutes then you will know you have poor residual fuel pressure . Note if you have not done this before seek help as this can be dangerous as you could set your car on fire .

Next , use fuel hose clamping pliers to pinch the fuel inlet hose ( having restarted engine and then stopped again ) . If the residual pressure drops you have a faulty check valve ( replace fuel pump ) . On the other hand if the residual fuel pressure stays remove the injectors and get them serviced . If the problem is still there replace the fuel regulator .

Note use an approved fuel pressure gauge - the fuel pressure is very high ( 250 - 500 kpa )










If the residual fuel pressure was ok do the same procedure on the fuel return line whilst

Apr 25, 2011 | 1993 Chevrolet K1500

1 Answer

Keeps giving P0171 reading any help


P0171- System Too Lean (Bank 1)

The adaptive fuel strategy in the vehicle's computer constantly monitors the fuel delivery system to make sure the engine is running at an optimum air to fuel ratio, which is 14.7:1. The computer adjusts injector pulse width to regulate the amount of fuel going into the engine. The oxygen sensors relay information to the Powertrain Control Module (computer), informing it of the oxygen content in the exhaust. This information is translated by the computer, and used to determine if more or less fuel is needed. The computer will then adjust fuel flow (and possibly other related engine operating characteristics), to keep the correct air fuel mixture. This loop continues as long as the engine is running.

A P0171 check engine light code is set when the computer has reached a rich calibration limit and can not add enough fuel to maintain the correct mixture.

Possible Causes:
The following is an overview of P0171 check engine light code possible causes.

Fuel System:

Leaking or faulty fuel pressure regulator
Plugged or dirty fuel filter or lines
Fuel pump weak or defective check valve
Injectors leaking or faulty
Low fuel pressure or running out of fuel
Leaking EVAP system components
Faulty FRP (Fuel Rail Pressure Sensor)

Air Intake System

Vacuum leaks
Contaminated, damaged or faulty Mass Air Flow sensor
PCV valve leak or stuck open
Air induction turbulance caused by wrong filter
Oil dipstick not seated
Air leaks after the Mass Air Flow Sensor (MAF)
Oil coated aftermarket air filter

Exhaust System

Any exhaust leak before or near the oxygen sensors

EGR System

Vacuum line disconnected from EGR System Module (ESM)
EGR valve, tube or gasket leak
EGR vacuum regulator valve leaking

Secondary Air Injection System

Mechanically stuck secondary air injection valve

Diagnostic Help:
A very thorough discussion of how to approach and repair a P0171 check engine light code can be found here. If you need further assistance let us know. Please be sure to stop back in and visit some of our other very useful site features to lear more about your car's emissions system.

Hope this helps (remember to rate this answer).

Jan 22, 2011 | 2000 Volkswagen Beetle

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2000 gmc jimmy wont start fuel pump comes on and cuts off but will not start.I have changed the fuel filter and that did not work. Is the pump not building the pressure it needs to start or would my...


the fuel pressure if leaking could cause this the regulator is located under the intake plenum but you should smell gas .if you dont then most likely the pump is bad ,the pump will come on for 2 seconds when the key is on then go off it will not stay on with just the key on only when you crank it will it .so have your fuel pressure checked with a gauge.

Mar 22, 2009 | 2000 GMC Jimmy

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