Author Topic: 85 Chevy K10 6.2L Diesel Fuel pump problems  (Read 7680 times)

Offline Yams

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85 Chevy K10 6.2L Diesel Fuel pump problems
« on: October 06, 2014, 06:16:42 PM »
Hi there, I'm new here, but here goes. As the title suggests, I'm having problems with a 85 Chevy k10 6.2L Diesel, specifically the fuel pump. I'm interested in buying this truck from someone, but not unless I can fix the fuel pump issue and drive it home. He's put a little work into it and said this about testing the pump and replacing it:

"I did the bucket trick with the old pump and a new one. Both pumps moved fuel on the bench but not when bolted onto the motor.    With the motor cranking you can feel the push rod moving. I also primed the pump with an external hand pump with it on the motor, that didn't help. I have primed the motor by using the return line and compressed air, no luck there either. The new pump is currently on the motor."

What do you guys think? My thoughts are that if the pump works, but isn't pumping, then it's either a blockage or a leak in the fuel line. So I was going to disconnect the fuel line leaving the pump and crank the engine, see if I get air being pushed out (if so, it would seems like a fuel line or connection is leaking air). If it's not pushing anything, then I would guess blockage in the fuel line. Test this by disconnecting the intake into the fuel pump and try to get fuel to come out either by gravity or an auxiliary fuel pump. If neither of those work out, I was thinking of just bypassing the mechanical pump and putting in an electrical one a la https://www.youtube.com/watch?v=OLDFZit_KzY

What do you guys think?

Offline fitz

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #1 on: October 06, 2014, 06:49:10 PM »
I have the same Mr Gasket green fuel pump in the video. I use it to test run 6.2's while bypassing the fuel tank & factory fuel filter. I hook the electric pump up to a 5 gallon fuel container and run it to a spin on fuel filter, then on to the 1/4" inlet on the injector pump.
Keep in mind if you get this truck running, he may want more $$ for it.  Are you buying this truck for cheap money?  Is it a far (expensive) tow home?  If you can buy it cheap and its close by I would think about buying it, getting it home, and getting it running at your house, not his.  If you get it running in his driveway before you buy it, you loose any bargaining power.

Offline Yams

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #2 on: October 06, 2014, 07:25:37 PM »
I think it might be easiest to just bypass the pump with the mr. gasket one... My plan is to try and agree upon a price before. he want's 2k for it (700r4 Auto Trans, NP208 t-case, Short bed, bumper ball, dual tanks, dual exhaust, pw, pb, ps, 155k miles + a tool box, four tires (30% left) and a couple miscellaneous parts. I'm thinking closer to $1500

Offline Yams

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #3 on: October 06, 2014, 07:26:46 PM »
It's 170 miles home so towing is not preferential

Offline fitz

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #4 on: October 06, 2014, 09:07:42 PM »
  If both pumps work on the bench but not on the motor, I would think the fuel line is blocked.   I don't see how bypassing  the mechanical pump will help, unless you also bypass the rest of the system.
  At first I was thinking it might be a clogged pick up tube in the tank, then I noticed you mentioned that it has dual tanks. Did you try switching tanks?

Offline Yams

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #5 on: October 06, 2014, 09:24:54 PM »
That's what I'm starting to think too just after some more research. I haven't tried that (gonna try when I go...). If it is a blockage in the fuel system, how do I fix that? Just pump the tank out then fill with diesel kleen? I could test for it by replacing the intake to the fuel pump with a line that comes from a jerry can...

Offline fitz

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #6 on: October 08, 2014, 06:30:23 PM »
A jerry can & electric pump should get it started.
I would not recommend driving it home this way.

Offline scottsdale92

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #7 on: October 27, 2014, 08:39:40 AM »
Like Fitz said it could be a block age in the line or tank, one problem I've ran into with those old diesels is a bent drive rod or slightly tweaked and another issue is a worn cam lobe.It feels and sounds like it's pumping but will not actuate the pump fully to get adequate pressure.
1984 chevy scottsdale LB 4x4

Offline roundhouse

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85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #8 on: October 28, 2014, 06:08:21 AM »
A jerry can & electric pump should get it started.
I would not recommend driving it home this way.

I'd drive it that way

If it were gasoline you'd wanna be careful
But Diesel isn't flammable
It's combustible

I'd probably take a couple good fire extinguishers anyway
Along with a spare tire and jack and good 4 way lug wrench
Tires are probably old and dry rotted

Strap the can in the bed  and zip tie new flex hose in to the engine compartments either down and under the cab or zip it to the passenger mirror and under the rear of the hood

As long as it doesn't get pinched
If there's a return line just make sure it goes back into the jerry  can also

I'd say the problem is in the line

It may have dual tanks.   But they share a line and switching valve

A tiny leak will cause it to suck air instead of fuel



But to see if it runs ok with no smoke or knocks  and the trans works ok. Brakes work ok etc   Just strap a can in and hook it up


A lot of times on old Chevys the rubber flex lines on the front brakes swell up inside and the brakes will grab and not release

You need to check all that before you


Also consider joining AAA

Free towing up to 100 miles

If its more than 100  just get em to take you 99 miles and drop it at a mall or somewhere

Have dinner and call AAA again for another 100 mile tow


BTW.  When you or the seller is cranking the engine
Don't run the starter more than 10 seconds and let it rest for at least one minute

Otherwise You will burn up the starter
If you have to replace the starter DO NOT buy one at an auto parts store
Find a place that can rebuild it
     The ones from auto parts stores are just used ones that have been cleaned and painted and tested
    They are not rebuilt


Also of you do get on your trip and the starter just clicks
   Have a helper hold the key while you smack the starter with a hammer

This will usually get it working again
Temporarily
 
At least a few times to keep you from being  stranded
« Last Edit: October 28, 2014, 06:21:32 AM by roundhouse »

Offline 78BIG-TEN

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #9 on: October 28, 2014, 08:50:29 AM »
Try putting a vacumn gauge on the inlet side of the pump,that should tell you if its working

Offline Yams

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Re: 85 Chevy K10 6.2L Diesel Fuel pump problems
« Reply #10 on: October 29, 2014, 12:23:41 AM »
So I just came on here to post another discussion and noticed my old post was still up so I figured i'd reply. Ended up buying the truck. The electric fuel pump worked great... Still haven't figure out what the problem with the mechanical one was, but don't really care... Another post about the truck with a bunch of questions if you're interested: http://forum.73-87chevytrucks.com/smforum/index.php?topic=29617.0