Mechanical question on my 98 limited HELP

Semper_Fi

Semper_Fi

New member
So sitting at a redlight today, my 3.4 quits on me, it cranks right back up, it does this a couple of times in the next 10 minutes, then it just cut off and would not start back up, now I have checked the fuel pump relay or replaced it anyway.

Are there any problems that I should know about before diving into the gas tank???? Even better yet, how do I diagnose it being the fuel pump and please keep in mind, IM NEW TO THIS TRUCK!!!!!!!!!!! Thanks for help in advance. :redbrick:
 
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Semper_Fi said:
So sitting at a redlight today, my 3.4 quits on me, it cranks right back up, it does this a couple of times in the next 10 minutes, then it just cut off and would not start back up, now I have checked the fuel pump relay or replaced it anyway.

Are there any problems that I should know about before diving into the gas tank???? Even better yet, how do I diagnose it being the fuel pump and please keep in mind, IM NEW TO THIS TRUCK!!!!!!!!!!! Thanks for help in advance. :redbrick:
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Try taking to fuel pressure reading off the rail. I think you can rent them for free at Autozone, or you can pick one up from Harbor Freight. I'd start here and see what kind of reading you get.
 
No need to drop the tank just yet. You can take the pressure reading from the fuel rail in the engine compartment with everything in place. Once you get pressure reading we can go from there.
 
MStudt said:
No need to drop the tank just yet. You can take the pressure reading from the fuel rail in the engine compartment with everything in place. Once you get pressure reading we can go from there.
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Roger that, It will be Saturday before I can get to it, its freaking 6 degrees here right now, we have a heat wave of the 40's coming this weekend
 
Semper_Fi said:
Roger that, It will be Saturday before I can get to it, its freaking 6 degrees here right now, we have a heat wave of the 40's coming this weekend
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I know the feeling, 2 degrees when I got up, 13 right now, and 2 again tonight. We'll be around 53 on Sunday for a high, and 13 for a high on Monday.
 
Semper_Fi said:
its freaking 6 degrees here right now
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Sounds like fuel line freeze-up. Get a bottle (or two) of isopropyl alcohol fuel treatment. If you select "Heet" brand, get the red bottle (Iso-Heet), as the yellow bottle is methanol, and doesn't do as good a job of absorbing/dispersing water.

No guarantees that this alone will solve your problem. The alcohol won't be able to find its way to the frozen section of the fuel line. But, as soon as the line thaws, you will have treated gas on its way to the engine.

There is a technique for thawing fuel lines using hot baked potatoes...
 
Riceye said:
Sounds like fuel line freeze-up. Get a bottle (or two) of isopropyl alcohol fuel treatment. If you select "Heet" brand, get the red bottle (Iso-Heet), as the yellow bottle is methanol, and doesn't do as good a job of absorbing/dispersing water.

No guarantees that this alone will solve your problem. The alcohol won't be able to find its way to the frozen section of the fuel line. But, as soon as the line thaws, you will have treated gas on its way to the engine.

There is a technique for thawing fuel lines using hot baked potatoes...
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I personally would not do this!

We do not live in a climate where this is necessary, and would not advise on doing it. This being said, if the line was frozen, chances of the vehicle starting at all are slim. With the way his climate is, 6 degrees is not norm, and is not enough to freeze the line. Where I live, we've seen -17 this year, and I've had not problems with the line freezing. There is another issue going on here.
 
Water freezes at 32F and if you are below that temp and suspect a ball of ice partially blocking your fuel filter, methyl hydrate will help and can't hurt if used in correct proportion to the gas in the tank.

It can be a problem here in some parts of Canada and it usually affects those who tend to run close to empty gas tanks
 
Why do you guys instantly think fuel? Dropping the fuel tank is a big deal, and in all the years of working on these things I have never EVER seen a failed fuel pump. If you really want to check the fuel pump, these is an access panel under the drivers rear seat. Pull the panel, then pull the plug off the top of the tank. The Two larger wires (Blue, and White) are the Power (Blue) and Ground (White). Apply power and ground where the wires would connect to the top of the tank, pull the fuel return line, and see if fuel is coming out. If it is, its not the pump, lines, or fuel pressure regulator. If not, THEN you have a fuel pump problem.

As for the HEET, there is absolutely NOTHING wrong with running a bottle of it in your tank. It will not hurt one bit. It's basically rubbing alcohol, which traps water and prevents it from freezing. Read up here: Heet FAQ's

I do however agree with MStudt, that is probably not your issue. It was 9 degrees here for a week and I use the cheapest crap I can find in my car, and not a single issue.

Start with the basics; Is it getting air, fuel, spark, is it in time.
 
Have you plugged in a code reader to see if there are any codes or pending codes (sometimes they don't send a CEL)?
 
DeathCougar said:
Why do you guys instantly think fuel? Dropping the fuel tank is a big deal, and in all the years of working on these things I have never EVER seen a failed fuel pump. If you really want to check the fuel pump, these is an access panel under the drivers rear seat. Pull the panel, then pull the plug off the top of the tank. The Two larger wires (Blue, and White) are the Power (Blue) and Ground (White). Apply power and ground where the wires would connect to the top of the tank, pull the fuel return line, and see if fuel is coming out. If it is, its not the pump, lines, or fuel pressure regulator. If not, THEN you have a fuel pump problem.

As for the HEET, there is absolutely NOTHING wrong with running a bottle of it in your tank. It will not hurt one bit. It's basically rubbing alcohol, which traps water and prevents it from freezing. Read up here: Heet FAQ's

I do however agree with MStudt, that is probably not your issue. It was 9 degrees here for a week and I use the cheapest crap I can find in my car, and not a single issue.

Start with the basics; Is it getting air, fuel, spark, is it in time.
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Great info, did know about the access panel, thanks, Ill start with a reading and if nothing Ill do this!
 
Semper_Fi said:
No, CEL is on, would that still read a code?
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If your check engine light is on, you probably have a code. It's not a bad idea to have your own reader too, I carry one at all times. If you pull a code, let us know what it is and we can go from there.

On a side note about the fuel pump. Flip the rear seat forward and remove that access panel. You can turn your key, but do not actually crank the motor. You should hear the fuel pump kick on for maybe 3 seconds or so, should sound like a buzzing noise. If you hear this, the pump is working and building up pressure in the tank, but how much pressure is hard to know. To find out how much pressure you'll need to take a reading off the fuel rail. It might not be fuel related, but it's pretty easy to check to make sure.
 
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yeah I messed up, I have no CEL light on is what I meant. Im going to pull the access panel and see if I can even hear or feel my pump kick in
 
Maf?

When I purchased my '97 it was randomly dying on me and it continued to get worse. Had the stealership look at it and they said it was MAF. I replaced it with an Oreillys MAF and 175k later it is running like a champ.
 
DeathCougar said:
Why do you guys instantly think fuel? Dropping the fuel tank is a big deal, and in all the years of working on these things I have never EVER seen a failed fuel pump. If you really want to check the fuel pump, these is an access panel under the drivers rear seat. Pull the panel, then pull the plug off the top of the tank. The Two larger wires (Blue, and White) are the Power (Blue) and Ground (White). Apply power and ground where the wires would connect to the top of the tank, pull the fuel return line, and see if fuel is coming out. If it is, its not the pump, lines, or fuel pressure regulator. If not, THEN you have a fuel pump problem.

As for the HEET, there is absolutely NOTHING wrong with running a bottle of it in your tank. It will not hurt one bit. It's basically rubbing alcohol, which traps water and prevents it from freezing. Read up here: Heet FAQ's

I do however agree with MStudt, that is probably not your issue. It was 9 degrees here for a week and I use the cheapest crap I can find in my car, and not a single issue.

Start with the basics; Is it getting air, fuel, spark, is it in time.
Click to expand...

Ran a hot wire to the fuel pump, it started running so where does the fuel Pressure gauge hook up at?
 
MStudt said:
No need to drop the tank just yet. You can take the pressure reading from the fuel rail in the engine compartment with everything in place. Once you get pressure reading we can go from there.
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Where is the valve to check the fuel pressure, I was looking for a Schrader valve but couldn't locate one
 
Semper_Fi said:
No, CEL is on, would that still read a code?
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You could have a code or pending code with no CEL. Driving my 4R one day, I heard a loud pop and then what sounded like an exhaust leak. No CEL. Got it home and found that a spark plug had popped out (pop and exhaust leak). The code reader showed a pending code for an exhaust leak (uhhh...)
 
I would forget about the fuel pressure issue to be honest.

Check the other things I listed first. I ran into this exact issue btw, and my Ignitor was failing. Somewhat common on these trucks.
 
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