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Old 04-03-2011, 04:04 PM   #1 (permalink)
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How to determine if fuel injector pump is bad?

I had a new starter put it. It turns fast but no go

The guy that put in said he's doesn't really know much about diesels. He cracked open the top of fuel filter and said fuel isn't getting in.

So what next? Could there just be a clog? I've never had a problem with the injector pump and I'm scared to death about it

Could a couple of bad glow plugs be the problem? Tell me a simple way to test them please
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Old 04-03-2011, 04:12 PM   #2 (permalink)
zetan
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Glow plugs test - use an ohm meter and read the resistance between the block and the glow plug terminal. Should be 1omh or less.
http://www.hummerknowledgebase.com/engine/gpt.html

No fuel at filter - while cranking in short bursts, open the fuel filter bleeder until fuel comes out, then close it. If nothing, your lift pump may be suspect. Disconnect the output side of the lift pump (mounted passenger side front bottom of block) and see if you get any fuel while cranking.

No fuel at injectors - make sure you hear an audible click of the fuel shutoff solenoid when the 12v power is applied to the pump power terminal. If the pump was replaced, you need to loosen all the injection line nuts and crank until fuel weeps out of the line, then tighten back down. The air bleeding process takes quite a while.
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Old 04-03-2011, 06:14 PM   #3 (permalink)
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Thanks zetan for the fast response. I tried the meter but didn't get ay reading. It stayed at 1. ohm. Guess I'm not doing it right

I tried bleeding the fuel filter but turning and turning the bleeder valve didn't do anything

A shot of WD-40 starts it right away, but that's not solving my problem, is it? I took it for a ride, shut it off and it started right away again. I'll try in an hour and see what happens

And this..."audible click of the fuel shutoff solenoid when the 12v power is applied to the pump power terminal" Sorry, I don't know what that means. Are you saying the problem could just be a solenoid?
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Old 04-03-2011, 08:05 PM   #4 (permalink)
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Zetan is giving a sort of non specific answer because he doesn't know all the symptoms of your truck. If the truck is running then the fuel solenoid is not the issue.

Opening the bleeder valve more won't do anything. It's like opening a faucet at home to find out if the water is running. If no water is coming out with the first few turns, turning it more doesn't help.
If you can't get a reading with the multimeter, try using a hair dryer stuck in the same place yu'd shoot the WD40. Run the hair dryer for a good 15 or 20 secs before you try to fire the truck up. If that doesn't help then glowplugs are unlikely to be the issue.

If there is no fuel coming out the fuel filter, then chances are good that the fuel pump is dying. Don't be confused into thinking that means the injection pump is bad. They are 2 different pumps. The fuel pump or lift pump just delivers fuel from the fuel tank to the inj pump. The inj pump does all the really hard work of delivering the fuel to the cylinders via the injectors. To test the lift pump, once the engine is running, open the bleeder at the fuel filter. The engine should stay running and the fuel should really squirt out. If the fuel just dribbles out then the pump is dying, and if the engine dies with the bleeder open, the fuel pump is done and the injection pump is sucking all its own fuel which is hard on it.
I know it's a long post but really there are only 2 steps. First try the hair dryer in the air intake. then try the air bleed with the engine running. Those 2 tests should show a lot.
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Old 04-03-2011, 08:20 PM   #5 (permalink)
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Hi smackzed

I recently moved and forgot the hair dryer. I will see if a neighbor has one tomorrow

I don't think the bleeder valve works. I turned and turned it and nothing happened

I replaced the lift pump because it was leaky about a year ago. (The little round can with a nob on top, located on the passenger's side, sort of in front of the starter?)

So I went and started it again after sitting for almost 2 hours and it started right up. Does that mean anything or is it because the engine is still warm?
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Old 04-03-2011, 08:46 PM   #6 (permalink)
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Sounds like because the engine is still warm. Maybe.

You turned the bleeder valve with the engine running and nothing happened?

I would try the multimeter again. Figure which glowplug is easiest to get to and scratch a shiny area on the engine or frame near that area. Turn the multimeter to ohms and touch the one terminal to the spade on the glowplug and the other terminal to the shiny spot then wait for a good 2 secs. If no change try scratching the frame or whatever with the terminal. I've found that helps.
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Old 04-04-2011, 01:34 AM   #7 (permalink)
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It sounds like the glow plugs are OK if she got 1.0 ohm and the spec. is between 0.8 and 1.0 ohm. Especially if the engine will start and run long enough to take it for a drive using WD40 as starter fluid. If the lift pump was changed about a year ago, maybe it was a reman. and not a good reman. at that. Probably needs to be replaced again. Sounds like the IP is doing all the work as smackzed said and perhaps the air bleed valve is plugged somehow.
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Old 04-04-2011, 03:04 AM   #8 (permalink)
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Really sounds to me like a bleed back problem in the fuel line. Or maybe just a slow air leak. Air in the lines can cause very hard starting if at all. But with running, shutting off and starting right back up it wouldnt have time to work back into the lines. Could be worth a check.
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Old 04-04-2011, 06:36 AM   #9 (permalink)
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I just discovered that even with a brand new mechanical fuel pump (the one mounted to the block you described) that the cam lobe was wore down enough that the pushrod wouldn't actuate it enough to properly pump fuel.

So after spending all that time and money trying to make that garbage work, i had to shell out more money again to buy a new universal electric pump. Now when the pump is on i can see fuel spewing out the bleed screw, when before i wouldn't get it even with the truck running.
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Old 04-04-2011, 07:36 AM   #10 (permalink)
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-82chev- I don't think she is getting a reading of 1.0 ohms. I think shes saying that her multimeter isn't changing at all.

6.2gal-make sure that your multimeter is on the lowest setting for ohms if it has different settings. mine has a few, from 200 ohms up to 200 000ohms. If it's on the highest setting it wont acknowledge anything under say 1000 ohms.
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