Fuel Pump

Boomer

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#1
Make
Chevy
Model
S10
Year
2002
Miles
148,000
Engine
4.3
All I can do is shake my head. I got the heater core done. Drove the truck to work. Everything was fine. I go to leave work, the truck fired up after barely even turning the key. Drive home, decide to stop for gas, (I had a half tank) get in truck to head home and cranking and no firing. Since I was stuck there, I pulled the relay and tried two others in it's place. Same result.

I had my uncle pull me home. I was only a mile or less from home. When I got it in the garage, I pulled the air breather off and shot some starting fluid into the throttle body. The truck started up.

My question is, would I be ok just replacing the pump itself?
I found this https://www.ebay.com/itm/New-AC-Del...ash=item541441f076:g:uw8AAOxyNmZTj5WO&vxp=mtr

I'm fairly certain the pump is what is going to go wrong as opposed to the entire assembly. Especially given the plastic doesn't corrode. Give me your opinions please.
 
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#2
Back in 93 with an S10, if you didn't get 55 psi, wouldn't start at all. Ours had that plastic fuel injector, shop manual said cheap, but not at our dealer, 700 bucks, but managed to find a rebuild on the internet for 200 bucks, plastic pieces were all broken under the upper intake manifold. Other problem the fuel line ran into the lower intake manifold with a rotten gasket causing air leaks, not easy to replace. Air leaks on this thing would cause the engine to run rough.

One thing that worked was to switch on the ignition switch three time, that would pulse the fuel pump for one second. Met a guy in the parking lot that would not start with a later model S10, told me to try that, he thanked me.

Was told, lucky to hold fuel pressure for 20 minutes, completely redid all the lines and the electrical, would hold for 24 hours. Compared this pump with my 92 DeVille, practically identical, but that car ran at 35 psi and only drew 4 amps, with the S10 at 55 psi, more like 8 amps, sucker really got red hot.

Just after fillup? Water in the gas? One thing you need is a good fuel pressure tester, and not one from Harbor Freight, 2 psi can make one heck of a difference. Sure was a job to remove that tank, muffler, cover, rusted tank bolts, all the fuel lines, three of them mounted on top of the frame, real easy to install before the body was dropped down, only about an inch of clearance.
 
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#3
"Pump only" can save some money. Just be sure to clean/tighten the wires where they connect to the pump support.

Some people raise the bed to get access to the pump.
 

Boomer

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#4
I raised the bed on my old 92 enough to do it. That’s what I have in mind here. Problem is a few weeks ago I was rear ended at a stoplight. It pushed the bumper corners right up to the bed. I may have to get the bumper off. I’m not sure yet. I can’t get the truck to the body shop to be fixed because stuff keeps happening!
 

billr

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#5
Have you really tracked it down to the pump? There is a lot more in the electrical power to that pump than just the relay. And, there is a lot more to proper fueling than just the pump/pressure. Using the starting-fluid only verified the ignition is OK, not much else. I would be doing more trouble-shooting unless that pump is really cheap and easy to change.
 

Boomer

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#6
Have you really tracked it down to the pump? There is a lot more in the electrical power to that pump than just the relay. And, there is a lot more to proper fueling than just the pump/pressure. Using the starting-fluid only verified the ignition is OK, not much else. I would be doing more trouble-shooting unless that pump is really cheap and easy to change.
No, I haven’t. It just happened last night so I do need to do more checking. I’m just preparing for the worst. I don’t know if there is room to get at the wiring at the tank or not. I was thinking of maybe the loaner tool program to check fuel pressure. If any of you would like to recommend a tester that does most GMs without breaking the bank, I may just buy one.

I’ll try to find a diagram for the pump circuit. I’m at work now, so I’ll look a little deeper when I get home.

With a full tank of gas, it won’t be easy to change for sure
 

nickb2

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#7
If you give 12v to the fuel pump prime connector in the fuse/relay box under hood, you should get the pump to go if the circuit and pump is good. If that happens, then the source to pump is the problem, not the circuit to pump and its respective ground at ground G402 on rear frame rail. Since you did get rear ended there, I would certainly check that ground out.

Here is the circuit. Check fuses, power to relay and respective grounds there to when key is on and cranking. Not much to this circuit.

I usually recommend just replacing the pump, not really need to replace the sending unit as well. Screenshot (181).png
 

nickb2

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#8
Although these kits are not a high end guage kit, it will do the job and you will have it for other cars you may need to diagnose in the futre. Most cars nowdays have a service connector in the USA dept. Yours is on fuel rail in engine compartment. Both come with the ford adapter also which is very useful to have when you know you are going to fix or own a ford in your life.

http://www.canadiantire.ca/en/pdp/equus-3640-fuel-pressure-tester-kit-0251020p.html

Or something like this will also do.

https://www.amazon.ca/8milelake-Inj...coding=UTF8&psc=1&refRID=54XRSEYZC1CTM8DSK49F

You are looking for KOEO pressure of 60-66psi.
 

jd

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#9
The "8-Mile" gauge set bears a strong resemblance to my Horror Fright set.
 

Boomer

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#10
If you give 12v to the fuel pump prime connector in the fuse/relay box under hood, you should get the pump to go if the circuit and pump is good. If that happens, then the source to pump is the problem, not the circuit to pump and its respective ground at ground G402 on rear frame rail. Since you did get rear ended there, I would certainly check that ground out.

Here is the circuit. Check fuses, power to relay and respective grounds there to when key is on and cranking. Not much to this circuit.

I usually recommend just replacing the pump, not really need to replace the sending unit as well. View attachment 10012
Thanks a lot for the diagram. I took my meter and was finding what the diagram indicates I should. I then decided to see if I could hear the pump run and low and behold, I could. I decided to fire it up and the truck started right up. I let it run for about 10 minutes and it ran fine.

Is the pump giving me a warning that it's weak? I got home late so I didn't check into the ground at the frame rail. Maybe I can do that tomorrow.

Have any of you seen a pump do this and then be ok for any good length of time? (if it's the pump) I'd like to run a bunch of gas out before changing it but, at the same time, I'm leery of being too far from home.

I'm pretty sure you guys have seen a lot of things.
 
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#11
Cut yourself a length of wire and power up that Prime Connector, just so you know what happens when the pump is working. (connect wire, hear pump run) Then put that wire in the glove box to test again when the truck won't start.
Possible scenario...truck won't start...install wire...no noise from pump...whack on bottom of tank with a broom handle...pump begins to run...start engine...remove prime wire...drive home...replace fuel pump
 
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#12
Did not have a second cup of coffee, see this is an S10 pickup instead of an SUV, but can also have electrical problems with both. In the SUV, ignition switch, relay contacts, and even the connector pins had dirty connections. Can find the by measuring the voltage as close to the fuel pump itself. Ours was losing 2.5 V, from 14.5, only 12V to the pump.

When this happens, that little tiny armature cannot come up to speed, that generates a back voltage that is lower than required so the current to the pump drastically increases really getting hot. And if the pump output cannot exceed the fuel regulator set point, no recirculating fuel to accelerate the destruction of the pump.

Also a 2002 vehicle, 2007 is when E10 was made law, E10 can really eat up a pump, but was still E10 available before then. A photo of a pre-E10 fuel pump armature, plastic expanded so much, it was jammed.
 

Attachments

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#13
Back in the 70's when leaded gas was banned, could put in thicker head gaskets, could only get 87 octane fuel, and pickup a later intake manifold with a carb with a venturi port with an EGR valve to run unleaded. Leaded was still available at three times the price, but with only about 10% of the lead in it.

With E-10, have to replace the entire fuel system, even the injectors with parts you can't even buy to really give us a huge amount of problems.
 

Boomer

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#14
Cut yourself a length of wire and power up that Prime Connector, just so you know what happens when the pump is working. (connect wire, hear pump run) Then put that wire in the glove box to test again when the truck won't start.
Possible scenario...truck won't start...install wire...no noise from pump...whack on bottom of tank with a broom handle...pump begins to run...start engine...remove prime wire...drive home...replace fuel pump
Yeah, from that diagram I’d go from ECM b fuse straight to the pump motor. I was trying kicking the bottom of the tank as well as rocking the truck up and down when I was stranded at the gas station.

The weird thing is I had a half a tank of gas so the pump “shouldn’t “ have been too hot.

Would you feel pretty nervous about getting too far from home? Does a fuel pump normally just quit and it’s done for good?
 

Boomer

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#15
Did not have a second cup of coffee, see this is an S10 pickup instead of an SUV, but can also have electrical problems with both. In the SUV, ignition switch, relay contacts, and even the connector pins had dirty connections. Can find the by measuring the voltage as close to the fuel pump itself. Ours was losing 2.5 V, from 14.5, only 12V to the pump.

When this happens, that little tiny armature cannot come up to speed, that generates a back voltage that is lower than required so the current to the pump drastically increases really getting hot. And if the pump output cannot exceed the fuel regulator set point, no recirculating fuel to accelerate the destruction of the pump.

Also a 2002 vehicle, 2007 is when E10 was made law, E10 can really eat up a pump, but was still E10 available before then. A photo of a pre-E10 fuel pump armature, plastic expanded so much, it was jammed.
Yep, pickup it is