6.9L Diesel Help
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6.9L Diesel Help
Hope someone can help im looking to buy an 87 F-250 6.9L Diesel and im told that it needs a fuel pump which is mechanical and it is on the block. My question is parts related. The truck will run on ether so its obviously not getting fuel, is it the fuel pump or could it be the fuel injection pump? or Both? I dont know much about diesel motors and is there a way to test to make sure which is bad bec i do not want to spend the $800 on the injector pump if i dont have to
thanks
nick
thanks
nick
Postmaster
Joined: Apr 2008
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There's very easy way to test the lift pump - on the side of the fuel filter head there should be a valve that looks like a tire valve, remove its core (with a tool for tire valves) and slip a hose on it and run the hose into a jar of some sort. Now crank the engine for 10 seconds - if the lift pump is in good working order you should have at least 1/3 pint of fuel in the jar. You can crank the engine by jumping the relay on the fender, no need to do it from inside the cab as that will also make the glowplugs come on and burn more of your battery reserve.
Postmaster
Joined: Apr 2008
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Yes, lift pump = mechanical fuel pump on the passenger side front corner of the engine block, same location as older carbed Chevy engines have them. If you do get good flow out of the lift pump, that only means it is good, it does not automatically say the IP is bad. For instance the fuel-shutoff solenoid (FSS) inside the IP could be bad (which can be replaced with the IP still on the engine), or it may not be getting power through the harness, or it could be something as simple as a severely plugged-up fuel filter...
To check power to the FSS - there are two electrical connectors on top of the injection pump, IIRC the front one is for the FSS, pull the harness off then stick a voltmeter lead in the harness connector and turn the ignition to "run" (all lights glow on the dash), you should have 12V or so at the connector.
To check the FSS itself - with the harness off its connector, run a jumper wire between the positive terminal of one of the batteries and the FSS spade connector tab on the IP - you should hear a fairly distinct "click" from the FSS every time you connect and then disconnect the jumper wire, if it's dead-silent it's probably just dead.
To check power to the FSS - there are two electrical connectors on top of the injection pump, IIRC the front one is for the FSS, pull the harness off then stick a voltmeter lead in the harness connector and turn the ignition to "run" (all lights glow on the dash), you should have 12V or so at the connector.
To check the FSS itself - with the harness off its connector, run a jumper wire between the positive terminal of one of the batteries and the FSS spade connector tab on the IP - you should hear a fairly distinct "click" from the FSS every time you connect and then disconnect the jumper wire, if it's dead-silent it's probably just dead.
