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rl_sd

Fuel pump or ???

14 posts in this topic

So I have a 1998 GMC suburban with a 5.7 motor that I have been having intermittent issues with. In the morning, it starts up immediately after cranking it over. When I leave work though, it becomes harder to start.  If I hit the key and hold it, it won't fire. If I cycle the key on and off a few times, it pops off. It used to do it occasionally, but now,has been a daily occurrence. I changed the fuel pump 6k miles ago and plan on doing it again this weekend. I have changed the fuel relay with no change. I am definitely leaning towards fuel pump but wanted your thoughts before sticking a $265 pump into it. Jeremy or anyone else... what do you think?

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13 hours ago, Macgyver55 said:

Have you replaced the fuel pressure regulator?

Haven't replaced the regulator, but I checked fuel pressure and am running at 65psi at an idle. The problem is when I dump the pressure out of the hose into a jug, it kills the engine. I tried another friends suburban (same year) and it runs fine... So I am thinking that I have a volume issue. Still doesn't quite explain why I need to cycle the key when it is warm.

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13 hours ago, leech~~ said:

How about the ignition switch it's self?

The switch seems to be operating correctly.

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2 hours ago, rl_sd said:

The switch seems to be operating correctly.

So it is cranking over each time you turn the key, but just not starting.  No dead spots when turned?

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37 minutes ago, leech~~ said:

So it is cranking over each time you turn the key, but just not starting.  No dead spots when turned?

correct... it just cranks and cranks and cranks. If I stop, cycle the key from off to run to off to run, it will fire right up.

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What brand of pump are you installing?

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38 minutes ago, Jeremy airjer W said:

What brand of pump are you installing?

Was thinking AC Delco. Thought about getting a Delphi, but it seems as thought the Delphi products aren't quite what they use to be.... thoughts?

Also, If I go the AC Delco route, do you know whether I need to order a sock strainer or does it come with one? I am looking at the MU1748

 

Edited by rl_sd

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That is one complete fuel pump module. Drop it in and your good to go.

If it is predictably acting up in the afternoon after work, have you tried checking the pressure pressure then?

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23 minutes ago, Jeremy airjer W said:

That is one complete fuel pump module. Drop it in and your good to go.

If it is predictably acting up in the afternoon after work, have you tried checking the pressure pressure then?

Yup. It is weird, when the air temp is warm and it is acting up, the pressure jumps around a little. This is all on the schader valve before the regulator. It still seems like I have a volume issue, although it could be something in the fuel regulator. Think that I am going to start with the pump since they are somewhat notorious to having a short life. Can you think of any other diagnosis before I put the pump in?

I have never done one but am fairly mechanically sound. Any tips? I looked on you tube and got the info that I needed. Even saw a few videos where guys cut access holes in the cargo area versus dropping the pump, which is tempting since this is just a hunting and fishing vehicle. But I didn't want to chance something catastrophic, you know... like blowing up!

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Drive it until it is empty. At about 7 pounds a gallon there is not sense in trying to muscle a 100+ pounds of fuel sloshing around.

Sometimes it is easier to unbolt the filler neck from the body (the part you put the gas pump in) and fish it and the rubber filler hose through the space between the body and the frame.

You will need these quick connect tools

Z-FKKwfo5oy.JPG

If you have the metal quick connect fuel lines at the pump. If they are the plastic ones you will not need them. They are made by OTC and available at any good parts store. This is the only one that will work with the plastic sending unit and metal lines without breaking the fittings off the moduel and then removing them from the lines.

take your time and drop the tank slowly. In addition to the fuel lines there are also EVAP lines that need to be disconnected. sometimes they can be hard to see and reach. Drop the tank a little and look around to see if anything else is following the tank as it lowers.

 

delcecchi likes this

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4 hours ago, Jeremy airjer W said:

Drive it until it is empty. At about 7 pounds a gallon there is not sense in trying to muscle a 100+ pounds of fuel sloshing around.

Sometimes it is easier to unbolt the filler neck from the body (the part you put the gas pump in) and fish it and the rubber filler hose through the space between the body and the frame.

You will need these quick connect tools

Z-FKKwfo5oy.JPG

If you have the metal quick connect fuel lines at the pump. If they are the plastic ones you will not need them. They are made by OTC and available at any good parts store. This is the only one that will work with the plastic sending unit and metal lines without breaking the fittings off the moduel and then removing them from the lines.

take your time and drop the tank slowly. In addition to the fuel lines there are also EVAP lines that need to be disconnected. sometimes they can be hard to see and reach. Drop the tank a little and look around to see if anything else is following the tank as it lowers.

 

Thanks Jeremy, I appreciate the input. I actually ordered the fitting disconnect tools when I ordered the pump today.  Do I need to drop the whole take or can I get by with dropping just the passenger side. I know that I need to disconnect the fill, vent and evap tubes either way, but saw it both ways on the net. What is your experience with the straps? Are they a PIA or do they come off pretty easy?

 

Here is the disconnect tool,I bought...

31XB0Q9pRWL._SX300_.jpg

Edited by rl_sd

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you will need to drop the whole tank to get enough clearance to actually remove the pump.

The straps are a dump shoot.

I have those style of quick disconnects but have never tried them for this job.

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