slow tow
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Senior User
Joined: Oct 2004
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From: ny
slow tow
well it seems my towing is slowing and the truck has a hard time getting the rpms up theses days fuel and air filters are fresh and fluids good . 87 7.3 idi with a 4 spd 4x4 f350 towing 3500 4000lbs weekly the truck has 180,000 the motor was a low milage jasper rebuilt when the last owner swaped the 6.9 for the 7.3 runs clean and dosent roll coal at all wich is leading me to think the ip is weak . shouldnt she make a little cloud when gettin on her im hitting grades at 55 - 60 and creeping at 40 - 45 shortly after drop a gear and hope she dosent get hot on a long climb whats up time for some real fuel system rehab or what ?
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
What is the fuel pressure...........
Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when starter cranking engine over. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of starter engine cranking, route fuel to a suitable container with a hose. When all finished hook up the FSS wire .
If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.
Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when starter cranking engine over. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of starter engine cranking, route fuel to a suitable container with a hose. When all finished hook up the FSS wire .
If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.
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Senior User
Joined: Oct 2004
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From: ny
So when i do the pressure test if i get six to nine pounds of pressure then we are determining the lift pump is good if the flow checks out right . i changed the mechanical pump last fall and didn,t see much differance . I will test it and see let you know how i make out.
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From: ny
So i just finished the pressure test and have a steady 5 psi at the purge valve and i get 8 + ounces of fuel when cranking for 10 seconds check the lift pump off the list and search deeper
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Joined: Apr 2009
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From: Malahat/Cowichan Valley
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Joined: Oct 2004
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From: ny
it has a stock style muff and who knows it could be a gasser style muffler i have never did nothing with it maybe i will drop it and put some thing strait thru ish on it . its a 4 speed and never rolls coal even when lugging up the steep ones at wot not haze or nothing
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From: Oregon
what elevation is it tuned for and what elevation are you towing at?
Mine started rolling some coal a mile high, since she's tuned for near sea-level, but you said yours wasn't. Nonetheless it was losing power like yours. Mine doesn't roal coal in town though. You get coal when ya got too much fuel or not enough air like I had in the mountains. If you turn the fuel screw enough you'll get coal or you wont ever - just depends what you set it at. Like Festus said, try upping the fuel screw some if ya got a pyro.
Mine started rolling some coal a mile high, since she's tuned for near sea-level, but you said yours wasn't. Nonetheless it was losing power like yours. Mine doesn't roal coal in town though. You get coal when ya got too much fuel or not enough air like I had in the mountains. If you turn the fuel screw enough you'll get coal or you wont ever - just depends what you set it at. Like Festus said, try upping the fuel screw some if ya got a pyro.
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From: ny
truck is in mountains of ny and is a daily driver i think after i get to install a pyro i will open the exhaust a little and then give her a flat or 2 of fuel i think the motor came from a fleet type truck its got the fuel filter on the drivers side side most ive seen are on the pass side in the pickups
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From: Michigan
truck is in mountains of ny and is a daily driver i think after i get to install a pyro i will open the exhaust a little and then give her a flat or 2 of fuel i think the motor came from a fleet type truck its got the fuel filter on the drivers side side most ive seen are on the pass side in the pickups
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