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Discussion Starter #1 (Edited)
Truck started missing going down the interstate at 75 mph.
just cleaned pre filter and new fuel filter last week ran great until today on the way home from work.
Over the last few weeks you could hear a small miss in the exhaust truck still ran great. Today
fuel psi is 30 and dropped below 20 under a load and right back up to 35 psi lift pump has 69000 miles on it. Truck idles fine You can raise rpm in park does as it should put it in gear with foot on brake and load it a little it starts missing, just ordered lift pump today has anyone had a problem like this? What problem will you see if you have a failing lift pump?
 

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When mine was on its way south, I could pass a car and surge forward hard before suddenly missing. I could gradually speed up to say 85-90 with no problem. Just if I laid into it. The spring was weak. No resistance when threading the cover back on.

Be cautious on cheap lift pumps off eBay. Some use a smaller piston. One I got didn’t even have the swarf cleaned out of the bore from machining. Want it?
 

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Discussion Starter #3
When mine was on its way south, I could pass a car and surge forward hard before suddenly missing. I could gradually speed up to say 85-90 with no problem. Just if I laid into it. The spring was weak. No resistance when threading the cover back on.

Be cautious on cheap lift pumps off eBay. Some use a smaller piston. One I got didn’t even have the swarf cleaned out of the bore from machining. Want it?
u
When mine was on its way south, I could pass a car and surge forward hard before suddenly missing. I could gradually speed up to say 85-90 with no problem. Just if I laid into it. The spring was weak. No resistance when threading the cover back on.

Be cautious on cheap lift pumps off eBay. Some use a smaller piston. One I got didn’t even have the swarf cleaned out of the bore from machining. Want it?
l ordered a new overflow valve, and lift pump. Maybe one of them will fix the problem
 

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Nothing like throwing parts at a problem. If you had 35 psi of fuel pressure the OFV is working fine.
 

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I did the ink pen spring in the overflow valve To get it up to 35 psi, before that it would idle at 20 psi and under load around 10 to 15. But as far as throwing part just trying to get what I need just in case it is one of these parts, for all I know could be a air leak, but something is causing the truck to skip under load and idle fine Fuel psi takes a nose dive when you load engine then but up.
 

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I didn't know that (how could I?). The ink pen spring is a temporary, troubleshooting type of fix so replacing the OFV is a good move. However, with only 69k on the lift pump I would have waited to see the results after installing a good OFV.
 

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I didn't know that (how could I?). The ink pen spring is a temporary, troubleshooting type of fix so replacing the OFV is a good move. However, with only 69k on the lift pump I would have waited to see the results after installing a good OFV.
Found number 2 injector not firing,I’m sure that where the miss is. Thanks for everyone help, once I do new set of rebuild injectors and overflow valve I. Hope I’ll be good to go
 
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