89 w50 still missing

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89 w50 still missing

Postby manostihl » Thu Dec 24, 2015 9:13 am

my truck shortly after i bought it developed an on and off miss when warm and a really bad miss when cold, it smokes when its missing too that smells of fuel. I just swapped out my stock who knows how old 9mm injectors for a set of brand new bosch 370h.p. injectors and although it runs A LOT better and smoother it still has the on and off miss when warm. when its cold it misses and puffs fuel smoke then run smooth then miss again and smoke more. The lift pump is a new stock replacement, fuel water separator is new, new 3/8 aluminum fuel line. The fss needs to be replaced i know that because sometimes i can rev it up with the key off and it will shut down and other times im not so lucky. could the fss be my problem? if not what else? delivery valves? pump tuning? im lost
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Re: 89 w50 still missing

Postby Remps » Fri Dec 25, 2015 9:26 am

Does it miss at an idle, or driving down the road?
'90 D250 R/C,727,IC,6x.009's,1/8" bump,fuel psi,straight pipe w/5" stack.
'90 W250 R/C,47rh,K@N,HX35,1/8" bump,2nd gen IC,boost,egt,trans temp.3.07's.
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Re: 89 w50 still missing

Postby manostihl » Fri Dec 25, 2015 12:17 pm

Remps wrote:Does it miss at an idle, or driving down the road?

seems to just be on and off at an idle especially when cold. runs great when youre on the throttle
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Re: 89 w50 still missing

Postby thrashingcows » Fri Dec 25, 2015 12:55 pm

Sounds like air getting into the fuel system to me.
1984/93 Dodge Crewcab, W350, 1 Ton SRW, long box, 330K Km's, M&H spacer, 366 spring, fuel pin to deep side, 14cm housing, Piston LP, PS IC, Isspro Boost, Pyro and tach, NV4500, 29 spline NP205, 3.54's.


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Re: 89 w50 still missing

Postby manostihl » Sat Dec 26, 2015 11:09 am

thrashingcows wrote:Sounds like air getting into the fuel system to me.

i thought that too but where could it be i replaced the feed line from the tank to the lift pump last year. i have no fuel leaks at the pump lines or the filter. i replaced the stock lift pump with a new delphi lift pump last year also.
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Re: 89 w50 still missing

Postby manostihl » Wed Dec 30, 2015 9:15 am

i cant find any fuel leaks anywhere . the injection pump was suposed to be new when i bought the truck
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Re: 89 w50 still missing

Postby manostihl » Wed Dec 30, 2015 11:07 am

could a malfunctioning ksb cause this?
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Re: 89 w50 still missing

Postby Remps » Wed Dec 30, 2015 9:08 pm

I'd try cracking one injector at a time when it is missing and see if one of them makes less of a difference in the way it runs, to rule out a delivery valve. Make sure the fss has a good connection, or remove the plunger for testing. Does raising the idle a little help any? I'd pressure the fuel tank to 5-10 psi and make sure there is no leaks.
'90 D250 R/C,727,IC,6x.009's,1/8" bump,fuel psi,straight pipe w/5" stack.
'90 W250 R/C,47rh,K@N,HX35,1/8" bump,2nd gen IC,boost,egt,trans temp.3.07's.
'96 2500 S/C L/B,2wd,NV5600,3.54 L/S,cai,egt,pacbrake,mbrp exhaust,10 plate.
Bring back the Bank of Canada, PRE- 1974.
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Re: 89 w50 still missing

Postby manostihl » Fri Jan 01, 2016 5:05 pm

ill have to give that a shot. i know the fss has a great connection even though its junk and needs to be gutted raising the idle dont help at all
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Re: 89 w50 still missing

Postby manostihl » Fri Jan 01, 2016 7:16 pm

it misses really hard and smokes a lot when its cold if you try to set the high idle to warm up.
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Re: 89 w50 still missing

Postby spencerdiesel » Sat Jan 02, 2016 6:19 pm

Both my friends truck and my truck have a small fuel fuel leak around the fuel filter base. Don't take this to heart, but I wonder if when the IP doesn't need/use much of the fuel delivered (hence the problem at idle), the pressure difference causes air to be drawn into the system?

Not trying to steal Thrashing's input :oops:
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Re: 89 w50 still missing

Postby manostihl » Sat Jan 09, 2016 1:02 pm

Could very well be as im still fairly new to the diesel world. I just don't understand how it could be an air leak when the smoke smells like raw fuel. Here's a vid of a start on a 32 degree day. She ran smooth for 15 or so seconds then started missing/smoking after she got some heat in her she hazed like normal but still misses on and off at idle and until about im guessing 1500 or so rpms ( im guessing because i dont have a tach) it runs pretty smooth driving you dont really feel it missing. Smokes a lot imo for having the smoke screw backed out as far as it is. Fuel pin is on max setting and the starwheel is about 2 3/4 from fully tightened down. The power screw was turned in about one turn in but I put it back to stock because it would hang in the rpms revving and in between gears driving.
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Re: 89 w50 still missing

Postby manostihl » Sat Jan 09, 2016 1:03 pm

manostihl
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Re: 89 w50 still missing

Postby manostihl » Sat Jan 09, 2016 1:11 pm

The colder it is. The quicker it starts missing on startup
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Re: 89 w50 still missing

Postby cougar » Sat Jan 09, 2016 1:18 pm

Does sound like air getting sucked into the fuel line. But if you can't fine the leak I'd suggest doing a compression check. You may have a low cylinder.
RIP 91.5 W250 5 speed. The great experiment.
92 W250 HD 47RH with Compushift. Upgraded H1C to 62/60/16, Scheid Lightning VE, 60# valve springs, DAP 7X.010 injectors, 4" DE exhaust, home made cooler tubes.
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