6.9 idi randomly dies when given throttle

[Van Anderson]

I have a 1986 Ford F-250 with the 6.9 and it runs fine when start it up and just kinda cruise around in 1st gear but when you start giving it throttle it starts running really rough and constantly dies and fights to start again and then continues dying. Does anyone have any suggestions?

 

[Thewespaul]

With the engine idling depress the Schrader valve on the filter head and see if fuel squirts out, sounds like you either have a bad lift pump or clogged fuel filter.

 

[Bio-Bradley]

I'm having the same trouble with my 7.3. I'll give that a try. I'm really hoping it's not the IP.
Thanks!

 

[Van Anderson]

I have put a new lift pump on it already, a new fuel filter, and held the button down and I’m getting fuel but it’s still doing it. I put an aftermarket electric pump on the frame a while back bc the truck didn’t have enough power to pull the fuel from the tank by itself and now it will leak a lot of fuel out of the water separator around the ring u pull. Do you have any more suggestions?

 

[Van Anderson]

Could the water separator leaking like that make it lose fuel pressure?

 

[Thewespaul]

Yes, many people bypass the water separator completely, or stick a bolt in the bottom to prevent leaks.

You do not want to run both the stock lift pump and an electric lift pump since the e pump will blow through the lift pumps diaphragm and fill the engine with diesel. You have to do one or the other, and if your lift pump can’t draw fuel then you have a clog before the engine that is your issue

 

[DieselRon1996]

Almost having the same problem with my 93 f350 7.3 idi...it will start up with no problems and idle all day..well sometimes...but it will shut down like it ran out of fuel ether driving down the road or just at idle..but if it’s up to temperature and it dose it and shuts down... it will take
45sec to 1 min of cranking to get it goin and that’s with pumping the throttle with it spitting and sputtering and I have to bump up the throttle once started to keep it running just so it will idle if not it will shut down but it dose it when ever it wants to

 

[Van Anderson]

Is there a filter on the bottom of the water separator and if so do I need to remove the filter and put the bolt where the filter is?

 

[IDIBRONCO]

No. The filter and separator are separate on the 83-86 trucks.

 

[Oledirtypearl86]

I have a 86 and had a bunch of issues with it right after I got the truck try bypassing it they can leak a lot of air and starve your IP of fuel needed

 

[IDIBRONCO]

I have a 86 and had a bunch of issues with it right after I got the truck try bypassing it they can leak a lot of air and starve your IP of fuel needed

It's pretty common to bypass it. Mine was already done when I bought the truck. It just saved me the trouble of doing it myself.

 

[Oledirtypearl86]

@IDIBRONCO they are a pain in the backside when they start to leak and can make the truck do all kinds of funny things everything from serging to hard starts

 

[IDIBRONCO]

@IDIBRONCO they are a pain in the backside when they start to leak and can make the truck do all kinds of funny things everything from serging to hard starts

DEFINITELY!

 

[johnf250]

I have a 1985 and was having the same problem. It’s probably your fuel tanks are rusted inside. Mine are and I plan on replacing them. The rust was so fine it made it past the stock fuel filter on the engine into the injector pump and looked like very fine mud. The water separator caught the bigger rust along with the fine and clogged up. I took the water separator off and cleaned it in a parts washer until I got all the rust out. It works fine now. I then went to Northern Tool and purchased two Goldenrod see through complete filter kits. One had the water separator filter which has I think a 17 micron filter and the other filter which has I think a 10 micron filter. I plumbed the two filter sets together and was able to mount under the hood between the fender and brake booster. The reason I used this type filter was because it’s small enough to install where I wanted it plus I could watch the filtering process. I then disconnected the fuel line to the water separator on the firewall and ran it to the Goldenrod water separating filter. The fuel now instead of going to the stock water separator go’s To the 1st Goldenrod filter into the second Goldenrod filter back through the stock water separator then to the stock filter on the top of the engine. The 1st Goldenrod filter catches 90% of the rust and rust mud. The second filter catches the rest. Occasionally I will drain the water separator into a clear glass and look at the fuel. So far there’s nothing in it it’s clear and clean. I haven’t had any more problems. You can tell when the filters need changing because you can see all the junk in the sight glass. Plus if you let it go too long without changing you will get a slight hesitation when you accelerate hard. Most of the time the Goldenrod water separator filter is all you need to change.