HELP! Injection pump or FSS problem?
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HELP! Injection pump or FSS problem?
I have an 89 f250 custom with the 7.3 IDI. I have been having troubles with the fueling system. A while back, I was driving and the fuel filter light came on and the truck slowly lost power and died. Put in a new fuel filter and it still would happen.
The truck would start and idle fine, although it would blow out white smoke when starting. But I would try to drive it, and I could get to about 40 MPH and the light would come on again and the truck would shut off. I stopped driving it, but would start it every other day and let it run for a little. One day it shutoff while idling, and I haven't been able to get it started since. I am getting fuel to the IP but not to the injectors.
Has anyone else had this problem or have heard of it? I have read forums where a guy was driving down the highway and his fuel filter light came on and truck shut off. But he couldnt get the truck started again. My truck would still start and idle and could be driven VERY slowly. But now, it won't even start. I just don't want to replace the injection pump to find out all I needed was a simple part. Any help would be greatly appreciated, thank you!
The truck would start and idle fine, although it would blow out white smoke when starting. But I would try to drive it, and I could get to about 40 MPH and the light would come on again and the truck would shut off. I stopped driving it, but would start it every other day and let it run for a little. One day it shutoff while idling, and I haven't been able to get it started since. I am getting fuel to the IP but not to the injectors.
Has anyone else had this problem or have heard of it? I have read forums where a guy was driving down the highway and his fuel filter light came on and truck shut off. But he couldnt get the truck started again. My truck would still start and idle and could be driven VERY slowly. But now, it won't even start. I just don't want to replace the injection pump to find out all I needed was a simple part. Any help would be greatly appreciated, thank you!
Elder User
Joined: Sep 2013
Posts: 594
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From: West Des Moines, IA
How much fuel is in your tanks? Usually when the fuel filter light comes on, there's a restriction or lack of fuel flow to it. If it's anything close to 1/4 tank, put 5 gallons in it and see what happens.
I've only had one FSS fail on me and have the pump still work, but it only worked for another 2-3 months and then completely failed on me, too. Easy way to check it is just jump the power wire on the driver's side with 12 volts. If you hear a click, it's working.
I think a more likely culprit is a fuel switching valve getting stuck in between tanks. Easy way to check that is take the feed line from your tanks off of the fuel pump, and put a fuel line on your pump down to a 5 gallon tank of fuel and see if it runs like that, so you're bypassing the on-board fuel tanks.
I've only had one FSS fail on me and have the pump still work, but it only worked for another 2-3 months and then completely failed on me, too. Easy way to check it is just jump the power wire on the driver's side with 12 volts. If you hear a click, it's working.
I think a more likely culprit is a fuel switching valve getting stuck in between tanks. Easy way to check that is take the feed line from your tanks off of the fuel pump, and put a fuel line on your pump down to a 5 gallon tank of fuel and see if it runs like that, so you're bypassing the on-board fuel tanks.
Laughing Gas
Joined: Dec 2013
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Is/was it putting out a lot more of white smoke than it usually does? The day my pump failed it took ether to start and smoked like a chimney, didn't have much power (not that it ever did) and just shut down on the highway. Definitely hard wire the FSS to rule that out, if you suspect fuel supply problems try idling it off a 5 gallon jug.
Lead Driver
Joined: Oct 2003
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From: Madison, WI
I think a more likely culprit is a fuel switching valve getting stuck in between tanks. Easy way to check that is take the feed line from your tanks off of the fuel pump, and put a fuel line on your pump down to a 5 gallon tank of fuel and see if it runs like that, so you're bypassing the on-board fuel tanks.
Logistics Pro
Joined: Sep 2007
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From: Western Mass
Sounds to me like the lift pump died. I had similar symptoms, the fuel filter light would come on when on the highway, or towing, but would be fine driving around town. Then one day it stalled out going through an intersection and wouldn't start again. New lift pump and all was well again.
These trucks have mechanical lift pumps on the lower front passenger side of the engine. Some people like to replace them with electric pumps, but I think the mechanical ones are fine.
To test the lift pump, disconnect the FSS so the truck won't start. Depress the schrader valve on the filter head and crank the engine. I can't remember the spec off the top of my head, but you should collect x amount in 10 seconds cranking. If nothing is coming out, disconnect the rubber line at the lift pump and connect a hose into a clean bucket of diesel. Repeat the test and see what happens.
These trucks have mechanical lift pumps on the lower front passenger side of the engine. Some people like to replace them with electric pumps, but I think the mechanical ones are fine.
To test the lift pump, disconnect the FSS so the truck won't start. Depress the schrader valve on the filter head and crank the engine. I can't remember the spec off the top of my head, but you should collect x amount in 10 seconds cranking. If nothing is coming out, disconnect the rubber line at the lift pump and connect a hose into a clean bucket of diesel. Repeat the test and see what happens.
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Thanks for the help, I am going to try it in the next few days and report back. We got a nice snow storm here and I haven't been able to go anywhere.
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Logistics Pro
Joined: Sep 2007
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From: Western Mass
Where you at? We just got another dump here in western mass. Not as bad as it could have been, but I've been avoiding going out to clear it. I'm just so sick of moving mountains of snow on a weekly basis.
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I'm in western Maryland, we got a little over a foot.
I checked the FSS today just by using a wire and connecting it to the positive terminal, it clicked so it's working, but I have to get a voltage meter to make sure it's getting all 12 volts. I have a strong feeling it's the injection pump, but find it weird that most other people couldn't get their trucks started after it went out. My truck could still be started and ran very slowly (noticeable loss of power) up and down my driveway. Then one day while it was running, it cut off and I could get it back on
I checked the FSS today just by using a wire and connecting it to the positive terminal, it clicked so it's working, but I have to get a voltage meter to make sure it's getting all 12 volts. I have a strong feeling it's the injection pump, but find it weird that most other people couldn't get their trucks started after it went out. My truck could still be started and ran very slowly (noticeable loss of power) up and down my driveway. Then one day while it was running, it cut off and I could get it back on
Logistics Pro
Joined: Sep 2007
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From: Western Mass
As far as I know, if the FSS clicks, its working. Full 12V or not, the clicking tells you its moving, and is not the problem.
Have you tested the lift pump yet? If you not getting any fuel to the injection pump, theres no way it the truck will run. Lift pump is much easier to troubleshoot and replace than the injection pump, and to me sounds like the problem you're having.
BTW, a bad injection pump should NOT cause the fuel filter light to go on. But a bad lift pump will DEFINITELY cause the fuel filter light to come on. A clogged fuel line, clogged fuel filter, and gelled fuel are also problems that will cause the fuel filter light to come on.
Have you tested the lift pump yet? If you not getting any fuel to the injection pump, theres no way it the truck will run. Lift pump is much easier to troubleshoot and replace than the injection pump, and to me sounds like the problem you're having.
BTW, a bad injection pump should NOT cause the fuel filter light to go on. But a bad lift pump will DEFINITELY cause the fuel filter light to come on. A clogged fuel line, clogged fuel filter, and gelled fuel are also problems that will cause the fuel filter light to come on.
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I have not tested the lift pump yet, but I am getting fuel to the injection pump, just not the injectors. I will check the lift pump sometime soon and report back.
But how can I check for clogging or gunk in the lines?
But how can I check for clogging or gunk in the lines?
