Intermittent power loss

[79jasper]

Also try bypassing the tank selector valve. Could have something clogging it now and then.

 

[Can30Diesel]

2psi at idle seems really low to me. Have you tried bypassing the mechanical lift pump with an electric one? Maybe the mechanical one isn't giving you the flow you need. I know I keep suggesting it, but there is also the possibility that the eccentric might have worn down enough that it doesn't drive the mechanical pump up and down fully which is why the new pump didn't change anything and WOT seemed to smooth out the idle a little.

 

[homelessduck]

The problem is only intermittent so I don't think it's an issue with the cam being worn. I will hook an electric pump to it anyway though, it would help narrow things down.

I'm not looking forward to dropping the full tank in the snow / mud, but it needs to be done so I'll be doing it today.

 

[homelessduck]

I haven't had time to drop the tank but I did run some fuel pressure tests.

Everything hooked up I'm getting ~2-3 psi at idle ( needle bounces from about 2-3 ) . Revving it up bumps the pressure to ~5-6.

I unhooked the supply line at the lift pump and ran a line into a can of my cutting oil mix ( I didn't have diesel and my cutting oil is almost identical viscosity) . At an idle it read a hair over 5. Obviously this is an improvement. Revving it didn't bring the pressure up.

It seems like when it's revved it has more suction so the pressure goes up, but at an idle it has low pressure due to a clog somewhere before the lift pump.

Does that sound about right?

 

[homelessduck]

I unhooked the fuel supply line at the lift pump and tried to blow through it. I blew as hard as I could but it was not enough pressure. I hooked the air compressor up to it and it was able to make the tanks bubble.

Should I be able to blow through it relatively easy?

I NEED this truck fixed TODAY.

Thanks guys! !

 

[79jasper]

I would think so. But I guess that depends on how full the tank is, and what fuel you're running. But does sound like something is/was clogged.

 

[dakotajeep]

To answer one your question on whether or not you have to drop the tanks to work on them: NO. I would actually lift my bed up with a lift from the ceiling in my garage. I would then drive out and have no bed to fight with. But you could just use some blocks of wood to give yourself the clearance to work. If you do go this route the are quite few lines, hoses and wires that need to be disconnected.

A thought about what could be causing your problem. I had an intermittent fuel delivery problem with my 94 F350 for two years. I tried a bunch of different things to fix it with no success. I even had it to a few shops (including a Ford shop) since mine would die and not restart. I replaced the FSV and that didn't work.

One day it hit me. The FSV was getting jammed up with particles from the "shower head". I put new fuel lines and inline filters on the both tanks and had no further issues.

My recommendation: Clean the plastic pieces out of your fuel tank immediately and install inline fuel filters prior to the FSV. At a minimum it gives you the knowledge that it won't come to haunt you down the road.

Thad

 

[homelessduck]

I'm definitely going to replace the lines and clean out the tanks.I've been so busy and haven't had time to drop them. Now I have to have it fixed by tomorrow. I live out in the country so I can't replace the lines today, this truck is my only vehicle.

I blew through the lines for awhile with the compressor. Now I'm able to blow through it pretty easily. I'm sure it was clogged. The problem is that it will just randomly happen again until I clean out the tanks.

I can drive on E so I'm sure my shower heads are still attached but who knows if there is broken ones floating around the tanks.

I have a steady 4psi at idle now.

 

[homelessduck]

I let it idle for awhile on the front tank then switched to the rear and let it idle another 20 minutes. Then I started to turn the truck around and it died. It did NOT want to restart. I switched back to the front tank and after awhile I was able to get it fired up and idling again. Hopefully it will run ok for me tomorrow and I can grab some fuel line and filters. The rear tank obviously has issues.

Thanks guys! !!!!

 

[Can30Diesel]

Glad it got up and working again! Not knowing whats wrong and having a deadline for it to be fixed really sucks, I have been there a few times now.

 

[homelessduck]

I didn't even make it out of my driveway this morning. It started up great (18* outside) . A few seconds later it died. It struggled to fire again. I finally got it running and it idle fine. I went inside to let it warm up. The second I sat down on the toilet it sounded like it died....but it came back to life and continued to idle. So I ran outside to check for visible problems, couldn't find any. I let it fully warm up and hoped it was going to be ok. I hop in and toss it in reverse. It sounds like it's about to die ( low idle) . I try to back out and it dies. I restart it and it idles really low and is obviously having issues so I shut it off.

I'm going to try to find valves locally today to switch it to a manual fuel tank selector.Hopefully I will have time to drop the tanks as well but I'm doubting it. I might be able to just block the bed up but I really need the tanks out so I can clean them properly. I really hope cleaning the tanks and eliminating the fsv works.

It ran great when I ran the fuel supply line in a clean can of my wmo. I'll try that again when I get home to double check. The issue has definitely become worse.

 

[79jasper]

Is this a automatic?
I've noticed some older ones don't like to reverse when cold. But that's with gassers.

 

[homelessduck]

Yes, e4od. It never had problems before. I'm sure it was just barely getting enough fuel to idle and when I put it in reverse it couldn't handle the load.

 

[79jasper]

Ah. I see. Well good luck. I bet it's still just clogging up.

 

[homelessduck]

Another possibility .. Would a clogged return line cause similar issues? Maybe it's clogged after the pump ..