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Discussion Starter #1
Hey guys first post for me...

I have a 1995 7.3 PSD I just bought it figuring I would give diesel a try, and realised that knowing nothing about diesels SUCKS! I am mechanically inclined when it comes to gasoline but thats where it stops...

So heres the deal... The truck has 160k in it and I drove it from boston to Pittsburgh and got 12 mpg! The truck has very little power and will barely maintain speed climbing slight grades. It is shuddering in the higher gears until it gets the rpm's up but it still has no power...

The turbo sounds fine, and there is not a ton of smoke. I replaced the fuel filter and cleaned the FPR screen.
both helped slightly, It does not shudder so bad but there is still some, and still no power.
My very non-professional opinion is its the lift pump. I have read about changing it on thedieselstop.com and is does not sound like it's that hard... has anyone done this without problem? are there any tips or tricks to this? And is there a recomended place or brand to get... and anything else that I should change while I am in there. And lastly does anyone have a more detailed linkfor this change... I know I am asking alot for a newbie but any help is greatly appreciated! Thanks for the help guys!!!!
 

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I would check the fuel pressure before you replace the pump. Just hook a pressure gauge to the 1/8" pipe thread that the shrader valve is screwed into on the regulator. Start up the truck and see what you gauge reads. I am not sure exactly what pressure the stock regulator is set up to run but someone will probably post that shortly. I would think you shouldn't see much of a problem with stock injectors at 45 or 50 psi. I run 60 psi on my truck with a electric pump from a SD.

You can shim the regulator to make more pressure but I would wait to do that until you have the pump diagnosed.

Changing the fuel pump isn't too bad, just make sure you are careful when removing the pump. Make sure you bring it straight up so you dont drop the tapet out of the pump. It wont fall out really easy normally but you dont want to take chances.

Steve Baz's site is a great place to read up on all the tips and tricks on the OBS Powerstrokes. I am looking for the link now.

Found it: Steve Baz's site
 

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Check that the exhaust back pressure valve isn't stuck shut. The linkage for it is on the bottom side, between the turbe and the down pipe. The linkage came loose on mine and I've heard of them getting stuck shut from carbon buildup. Fully clockwise looking from the top is open.
 

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If you do change the lift pump, change all the fuel hoses that are close by too. Got my pump at car quest.
 

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Discussion Starter #5
changed the lift pump

Changed the pump tonight... that sucked!
What sucks even worse is it still ain't fixed...I will try the other things tomorrow and see if it helps...Thanks alot for all the help... it seems like nobody around my town has any clue about diesels.... Thanks again...
 

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Definatly replace the three little hoses going to the pump, if you have to replace the pump you'll probably rip them removeing it anyway. I think they are heat resistant so I bought mine from ford they come cut to length so that maks it easier. also there are two washeres that seal the line on the back of the pump you probably need to get them too.
 

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broadheadjohn said:
Changed the pump tonight... that sucked!
What sucks even worse is it still ain't fixed...I will try the other things tomorrow and see if it helps...Thanks alot for all the help... it seems like nobody around my town has any clue about diesels.... Thanks again...
I'm a slow typer you posted that while I was typing mine in.
Your not getting a check engine light or anything are you?
 

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Discussion Starter #8
Jared S said:
Check that the exhaust back pressure valve isn't stuck shut. The linkage for it is on the bottom side, between the turbe and the down pipe. The linkage came loose on mine and I've heard of them getting stuck shut from carbon buildup. Fully clockwise looking from the top is open.

No check engine light....
I looked for the exhaust back pressure valve... is it right next to the turbo on the bottom of the pipe with the rod that goes behind the turbo? If so, I pushed on it and it moved a little, but it does not move when pushing the throttle...
 

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broadheadjohn said:
No check engine light....
I looked for the exhaust back pressure valve... is it right next to the turbo on the bottom of the pipe with the rod that goes behind the turbo? If so, I pushed on it and it moved a little, but it does not move when pushing the throttle...
yes it is on the bottom exit side off the turbo. the only time it will move is when the engine and the outside air is cold. It will close to make the engine warm up faster. I dont think you should be able to move it verry much by hand but I am not sure.
When you replaced your fuel filter was it very black and oiley you could have an injector O-ring leaking oil in to the fuel and causing problems.
Also If you checked your fuel pressure what was it.
 

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Discussion Starter #10
I will check the fuel pressure today... the fuel filter was not to bad...the FPR screen was pretty clogged, cleaning it helped some...I will let you guys know the fuel pressure asap. Thanks again.
 

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I went out to start my truck today for the fuel pressure and the truck WON'T START!IT DOES NOT EVEN TRY TO START! I cranked the hell out of it and nothing... just once it turned for a split second and now nothing...I let it sit for an hour and it still just spins. Any thoughts before I cry softly to myself in a corner.
 

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Discussion Starter #12
just did some reading found this... I'll give it a try...

"I would suspect that the GPR (Glow Plug Relay) is not working correctly. When the GPR gets worn out, not enough voltage can make it to the glow plugs, and consequently, they do not get hot enough for the engine to start.

You can verify this by measuring the voltage ACCROSS the two LARGER GPR terminals with the "Wait to Start Lamp" on. Your reading MUST be lower than 0.5Vdc (1/2 volt), if it is more than that, the GPR is BAD"
 

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are you getting any smoke while cranking? if yes then u have fuel to the cylinders if no then then you dont. not sure what all will cause no fuel if u already changed pump
 

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I am getting fuel, its smoking when I crank... I checked the voltage on the GPR and the only reading I got was a .o2 as soon as the key turned and then o.oo .... I tryed jumping the two big terminals and it did nothingh, no spark at all. So I would assume the gpr is bad????? It was getting 8-10 volts at the smaller terminals... I guess I am going to change the relay. Thanks, John
 

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sounds like relay my buddy had same problem and that fix his so let us know
 

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well I was getting no spark because my wire shorted and completly blew the wire out...so I fixed that. now I have 11-12 volts at the glow plug relay but even when I bridge the two large terminals with a screwdriver to bypass the the relay it won't start... This is driving me CRAZY! Should I change the relay?
 

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I know this isnt a fix by any means. However.


How long are you bridging the connection between the two big terminals. 5 seconds, 10 seconds? Try doing it for about 30 seconds. The PCM normally determines how long they stay on, up to two minutes.


Does the relay go "CLICK" when the ignition is turned on?

Your low power issue. Does the truck idle smooth? I.e., does it rock any, or is it smooth?

After you get it started, ( do not use any ether) and get a fuel pressure reading, go to wal-mart and get a 32oz bottle of power service Diesel Kleen. Pour the entire thing into one of your tanks, fill the tank up, and drive it. The bottle says use 8oz for 10 gallons? However, this just is not a strong enough mixture if it has never gotten this ran through it. This will clean the injector tips.

IF you must get the truck moving, and you do not have power to your GPR at all. You can do one of two, or both things.

1. If you're equipped with a block heater,(look for plug under front bumper) plug the truck in for a couple of hours, should start then.

2. If you are not equipped with a block heater. Get a hair dryer, run it for a bit and shake it about, to get any junk out of it. Remove the air filter cover, and stick the hair dryer into the intake. Crank engine, the hot air should get the intake air hot enough to light it off. May take a few seconds of cranking though.

I was in the mountains last year when my GPR took a dump. My block heater is burnt out. I had to use.. the Hair Dryer method to get it started.

I hope this helps some, until someone who knows something about the Electrical System on these trucks chimes in.

Take Care, and merry christmas!
 

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Discussion Starter #18
It idles faily smooth... I have never heard it run without problems so I have no "standard" for it. I will try bridging them longer. I am pretty sure the gpr clicks when you turn the key.

So if it clicks then the relay is good?????
Mabey my plugs are bad??? or does that happen over time and not instantly over night???

the wire shorted because I dropped a wrench across the GPR...
It blew the wire out all the way back near the starter relay on the fender. It blew right in front of the 14 ga inline fuse so I just cut the fuse and about two inches of wire off and hard wired it with no fuse... Its a little rigged but it got me power to the GPR...
 

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Got the truck started with ether....there is still no power though... I can't find a pressure tester for diesels... do any of you guys think it may be the computer???
 

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If your just checking fuel pressure any old pressure gage will do. I'd just get me a cheep oil pressure gage that will go up to at least 60 psi. it should have every thing you need to plum it in to the 1/8 fitting in the filterbase.
I think you should be running about 40 psi while running.
 
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