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Discussion Starter · #1 · (Edited)
2001 4.3 auto.



Replaced the filter and pump about 5 years ago, leas than 10k since then.
In the last 6 months,
If I dont let the pump properly prime, first start of the day is difficult, it will start but runs poorly / misses for 30 seconds or so, then Ok.

I had an episode on the highway where the car surged / hesitated for several miles about 8 months. Did it only that trip, no further thought.
This last week, waited proper time for priming but still started rough, then city driving was poor, lots of hesitation.
Now, wont start at all, check engine light now on.
Would like to do a few things, check for spark and if so, change fuel filter. Bought a new filter and started draining the line at the filter and it seems like it just pissing out fuel, how much can come out?
Isnt it only the fuel in the line, no matter how much fuel is in the tank?
Should I have released fuel line pressure at the valve by the distributor?

Hopefully its the filter, should I get a gauge and measure at that valve, or just change the filter no matter what?

Thank you.
 

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2001 4.3 auto.

Replaced the filter and pump about 5 years ago, leas than 10k since then.
In the last 6 months,
If I dont let the pump properly prime, first start of the day is difficult, it will start but runs poorly / misses for 30 seconds or so, then Ok.

I had an episode on the highway where the car surged / hesitated for several miles about 8 months. Did it only that trip, no further thought.
This last week, waited proper time for priming but still started rough, then city driving was poor, lots of hesitation.
Now, wont start at all, would like to do a few things, check for spark and if so, change fuel filter. Bought a new filter and started draining the line at the filter and it seems like it just pissing out fuel, how much can come out?
Isnt it only the fuel in the line, no matter how much fuel is in the tank?
Should I have released fuel line pressure at the valve by the distributor?

Hopefully its the filter, should I get a gauge and measure at that valve, or just change the filter no matter what?

Thank you.
Nothing more fun than gasoline bath changing filters. Real cold gas can even cause freeze burns. Ya , if filter doesnt help , fuel press ck advised as next step.
 

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Discussion Starter · #3 ·
I tried a fuel pressure check today, zero pressure which I assume means the fuel pump crapped out or the filter is extremely clogged, which seems unlikely.
Battery was running low nut I believe sufficient to engage the pump. Charging now and will try again once it regains some juice.
Question, if I remove the filter and turn the key and gas doesnt come rushing out, does that for sure mean the pump is bad?
Or does the pump need some sort of line resistance to operate?
It would be great of the pump would push out fuel then I would know its
Filter
Regulator
Or a stuck open injector(s)

Is this sound correct?
This pisses me off considering the fuel pump has 6 years and under 10k miles on it.
Knowing that, whats the best, reasonably priced replacement pump?

Thank you.
 

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Thanks Rhot, do my rhoughts and theories about a preasure test make sense?
Read this....it has all the info you need.

 

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Discussion Starter · #7 ·
Thanks again Rhot, now a few more questions;

Where is the terminal in the fuse panel where I can bypass the relay and activate the fuel pump?

Where can I get an adapter to test the pressure at the exit of the fuel filter?

And now probably the worst question, how does one know the fuel pump is being powered, by hearing the whine or is there some other method to determine with certainty the fuel pump is running, even if not running properly?

Thanks again. Trying to solve this but there is a possibility I have it towed to a $hop and pay thrunthe no$e.
 

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I'd check pressure at the Schrader valve 1st. If the filter is new, I wouldn't worry about testing pressure at the filter. You'll hear the pump whine once it has power to it. Here's a pic @oldeerslayer posted in a sim liar thread..

Electronic component Audio equipment Electrical wiring Electronic engineering Gas
 

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Discussion Starter · #9 ·
Thanks, I did swap that relay out with one for the horn, as suggested in a Youtube video I watched, no change. Also checked the fuse.

So with that red arrow pointed to an unused spot in the fuse panel, if I run hot to that, it will trigger the fuel pump?

I have a hard time hearing the pump with the bells that start the moment the key is turned on, can I kill the bells?
 

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There's a hot post in the upper left of the pic. Jump from there to the spot on the fuse box. If the pump is good, the pump will run non stop. Jump the box and try to start it.
 

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Make sure the ground lug on the frame, driver side, back by rear bumper is clean and tight. That ground lug provides ground for the pump.
 

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Discussion Starter · #12 ·
Rhot ans Rimara...I bypassed the relay and started the pump, it is operational and jumps to 60 pounds but then fades fast but, I checked at the valve / gauge coupler and it leaks so I dont know if the system is tight or not. At least I know the pump fires although its effectiveness remains in limbo.
The gauge is a rental from AutoZone, so I dont know how to get it to properly seal and remain tight. Any ideas?
Here is a video I shot of the gauge, prior to realizing the gauge was pissin out fuel.

Thanks again.

 

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Could be either a leaky injector or FPR. It's not that hard of a job to pull the upper intake and look for washed spots where the gas is leaking from. You could pull the poppets/injectors and hook the fuel line back up and turn the key on and see if there's a leak. I would do this outside and disable the ignition and have a C02 extinguisher handy....just in case.
 

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Discussion Starter · #14 ·
Rhot, as always; thank you If what you suggest is the next step, I likely won't be doing something like that...just not in my wheelhouse, Also, knowing the Guage coupler is leaking, am I certain there is a leak other than that? I'm going to try and get that sealed up better, or is that a useless exercise?
 

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If you're talking about the gauge from AZ...take it back and tell them it leaks. If they don't have another, try a different store.
 

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Discussion Starter · #16 ·
Will do, should have thought of that.
Something which may give you more food for thought it this truck has always got horrible city mileage. I read somewhere that is a symptom of fuel related issues; thought you may like to know that

Thanks again.
 

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Start with a fresh fuel pressure gauge. After you get the results from that, we can tackle mileage. What kind of mileage are you getting?
 

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Not the greatest…but not terrible either. What have you done as far as a tune up? What brand parts did you use? 4.3’s are kinda picky and like OEM parts.
 

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theres a lot going on here.
I bypassed the relay and started the pump
Attach the fuel pressure gauge to the schrader. Does the fuel pressure gauge move when you have the relay plugged in and turn the key to prime the pump? It wasn't too clear from the way you typed it. I doubt two relays are junk but... ya never know.

Be careful leaking fuel, the distributor cap is right there...
You definitely need a non-leaking gauge to perform all of the pressure tests in the sticky linked previously. Screw it on tighter or take it back for one that doesn't leak.

What is the voltage and age on this battery? You need to load test it or have it load tested...
What are the codes it is throwing?
You can have them load test the battery and check codes at the part store... assuming they actually know how to do a load test. Many minimum wagers at the parts store don't know.

You mentioned that the pump is a replacement... bad wiring splices are common with replacements, as is the bad ground mentioned previously.
 
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