Big Help Needed, No Start
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
Have someone crank it while you check the fuel pressure. If the pump isn't working it won't start even if there is fuel in the bowl. It is a two stage pump and it has to pressurize the fuel rails in the heads in order for the truck to start. It won't gravity feed. You're looking for something like 20 PSI of fuel pressure while you are cranking it. Use a rag to shield yourself too, you don't want a diesel shower!
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Tuned
Joined: Feb 2010
Posts: 339
Likes: 0
From: Texas
Well, Nate, here's the thing. I don't know if it's the way it's wired or what, but while the engine is cranking, the gauges don't have power. It's the same with my radio too, when you turn the key to on and what for glow plugs, the radio is on, while you turn key to start, radio is off. Same thing with my gauges. That's why I don't know what my cranking fuel pressure is. But I can tell you that while I had it running on Monday, it was at 45psi, then I watched it go down to 0 and die. That was the last time it was running.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
The radio is supposed to go off with the key in START. So you have an aftermarket electrical fuel pressure gauge with a sender/sensor permanently connected to the fuel system? If so, the raw power to that gauge is probably on the same fuse/circuit as the switched power for the radio, which is why you can't use it while cranking. Option - until you get this resolved, rewire the gauge so the raw power feed is from some unswitched source, so it feeds the gauge power no matter what position the key is in.
Or, as stated, check fuel pressure while cranking with a mechanical gauge connected to the schrader valve.
Or, as stated, check fuel pressure while cranking with a mechanical gauge connected to the schrader valve.
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Tuned
Joined: Feb 2010
Posts: 339
Likes: 0
From: Texas
OK, a little update here. Still cannot start. I have changed out the CPS, since it was cheap enough to do anyway. The GPR is good, I tested both terminals, 12v at off and 12v at on. I tested the uvch connectors for the glow plugs, resistance at about 4ohm on all of them, if I did it correctly. Batteries are all charged up, yet it still reads low in the cab and acts like it is not getting enough juice to start. Cleaned the FPR screen, which had a little bit of gunk on it. What am I missing here? Why won't she turn over?
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
Is it cranking at normal speed or just so / so?
I think you need a fuel pump. Have you tested the fuel pressure yet while someone cranked it?
You can inspect all the battery leads for signs of corrosion inside and look at all the grounds, take everything apart and clean up the contacts. You can also unhook either one of the small wires from the GPR to disable the glow plug system. If voltage is an issue, having the GP's unhooked will allow for a little more juice for the starter. It should start without the GP's unless it is really cold out.
Or you can check the fuel pressure. I'm not sayin'n that's the issue, I'm just sayin'....
I think you need a fuel pump. Have you tested the fuel pressure yet while someone cranked it?
You can inspect all the battery leads for signs of corrosion inside and look at all the grounds, take everything apart and clean up the contacts. You can also unhook either one of the small wires from the GPR to disable the glow plug system. If voltage is an issue, having the GP's unhooked will allow for a little more juice for the starter. It should start without the GP's unless it is really cold out.
Or you can check the fuel pressure. I'm not sayin'n that's the issue, I'm just sayin'....
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Tuned
Joined: Feb 2010
Posts: 339
Likes: 0
From: Texas
I can't really tell if it's cranking at full speed or not. tach moves to 150-200ish. I just connected my gauges to a hot all the time point and cranked it, needle for fuel pressure didn't move a bit.
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Thread Starter
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Tuned
Joined: Feb 2010
Posts: 339
Likes: 0
From: Texas
Just to be certain, I'll take the sender unit off and check it with a mechanical too, but I guess it's time to slap in another new fuel pump. I have a hard time understanding how the one in there could go bad after only 20 months or so.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Then there's something wrong, probably downstream, with the glow plugs. Voltage with the key in RUN should be considerably lower than with the key off. If the voltage is the same, then the glow plugs aren't drawing current, and probably aren't working.
Did you measure the voltage at each of the big terminals? The other important thing is that, with the key in RUN, the voltage at the "always hot" big terminal should be no more than 0.3V more than the voltage at the switched big terminal. Or you can measure the voltage _between_ the big terminals (red probe on the always hot terminal) while the key is in RUN; that voltage should be no more than 0.3V.
That's too high. they should be about 1 ohm each. High resistance --> low current --> glow plugs not actuall glowing (may also explainthe voltage not changing).
Did you measure the voltage at each of the big terminals? The other important thing is that, with the key in RUN, the voltage at the "always hot" big terminal should be no more than 0.3V more than the voltage at the switched big terminal. Or you can measure the voltage _between_ the big terminals (red probe on the always hot terminal) while the key is in RUN; that voltage should be no more than 0.3V.
I tested the uvch connectors for the glow plugs, resistance at about 4ohm on all of them, if I did it correctly.
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Tuned
Joined: Feb 2010
Posts: 339
Likes: 0
From: Texas
I'm not saying they're always right, by any means, but I had the starter tested at oreillys and it tested good. I just can't figure out why I don't have enough juice for it to turn over. It has 2 new batteries in it now too.
Junior User
Joined: Oct 2009
Posts: 74
Likes: 0
I had two good batteries and a starter that tested good, but I bought a new one anyway and the truck turned over much faster. sometimes when they go bad they draw a lot more current and don't turn over as fast. Guy at the autoparts store thought I was nuts buying a new starter when he just tested mine as good. But I had already ruled out everything else. Just wanted to comment on this, not saying it is what is wrong with your truck.
Junior User
Joined: Oct 2009
Posts: 74
Likes: 0
Another thing that happened to me is the end of my pick up tube broke off in my tank and I would run out of fuel at around a quarter of a tank on the gauge. It's a metal line down so far then there is a rubber like cone on the end that broke off.
Fleet Owner
Joined: Aug 2004
Posts: 20,419
Likes: 197
From: AZ
I had two good batteries and a starter that tested good, but I bought a new one anyway and the truck turned over much faster. sometimes when they go bad they draw a lot more current and don't turn over as fast. Guy at the autoparts store thought I was nuts buying a new starter when he just tested mine as good. But I had already ruled out everything else. Just wanted to comment on this, not saying it is what is wrong with your truck.
Storm, that's exactly what I was trying to say. The auto parts store tester just can't put the load on them to test them right. Same with me, mine tested good, I bought a new one any way and away I went!!