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Aug 28, 2018 | 09:19 PM

allentown09

Thread Starter

New User

Joined: Jan 2018

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Need help again!

ok everyone I have a 1985 f25o with a 351w the truck will fire up and stay running as long as I’m supplying it with fuel either spray starting fluid or by using the throttle? Could my fuel pump be bad or what? Any and all help appreciated.

Aug 29, 2018 | 09:02 AM

jackietreehorn

Cargo Master

Joined: Oct 2016

Posts: 2,738

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From: Northern VA

Disconnect fuel line from carb and crank. Should fill up a coke bottle in less than 30 seconds.

Could have vacuum leaks or carb is way out of adjustment.

Aug 29, 2018 | 12:01 PM

82_F100_300Six

Cargo Master

Joined: Jun 2008

Posts: 2,875

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If this suddenly happened recently it's possible that your truck dieseled after shutting off and it coughed out a vacuum cap.

Aug 29, 2018 | 12:46 PM

Rusty_S

Lead Driver

Joined: Apr 2007

Posts: 5,958

Likes: 105

From: Houston

If it stays running with you giving throttle then its not a fuel pump issue its a carb issue. might have dirty jets or maybe even a dirty fuel filter. Possibly even a dirty air filter but I assume you tried running it without the airfilter assembly.

Aug 31, 2018 | 02:26 PM

MikeIronTyson

Junior User

Joined: Apr 2018

Posts: 80

Likes: 1

sorry I posted on wrong thread and do not know how to delete this.

Sep 1, 2018 | 05:33 AM

FuzzFace2

FTE Legend

Joined: Nov 2015

Posts: 30,830

Likes: 4,096

From: Angier, NC

Quote:

Originally Posted by 82_F100_300Six

If this suddenly happened recently it's possible that your truck dieseled after shutting off and it coughed out a vacuum cap.

Ok so if it does stay running with throttle then as said not the fuel pump or filters, air or gas.
If bed pump then would not run with throttle, same with a bad fuel filter because of no fuel to carb.
Bad and it would have to be REALLY BAD air filter it would run really rich (to much fuel) or not at all.

My guess even if it did not diesel (sneeze) is a vacuum plug fell off causing a big vacuum leak that cant be overcome at idle or idle jets in carb are plugged.
Let us know what you find.
Dave ----

Sep 1, 2018 | 12:53 PM

82_F100_300Six

Cargo Master

Joined: Jun 2008

Posts: 2,875

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Thanks Dave yeah I think sneeze is a better description.
this happened to me about six months ago. I could have easily and conveniently retrieved the rubber vacuum cap underneath the truck where I had shut it off but unfortunately I had driven off before I figured out what happened.
On mine there is a three or four inch "vacuum tree" and that is where it was missing.