Hi guys. .. I hope y'all are doin' well .. So my trucks been parked awhile, she been running like a champ for about the last three weeks when i put her back into primary service .. But all the sudden she has issues, major issues .. I haven't had anything like these symptoms before, and they're very strange erratic behavior . I would like opinions - suggestions of what to look for here to fix this .. so about last week i was crusing down the highway and the ol' girl surged and gathered speed without pedal, then immediatly after lost power and slowed to 60mph .. That was the first instance and it didn't happen again at first so I thought it a fluke, well it did it again about 3 days later, then started running fast, like I put a supercharger on it .. Super fast pedal response but it would surge maybe 2 seconds after I let off the pedal. Then it started idling high all the time, and seemingly missing and sounded more clanky and the whole motor kinda had a steady buck, well at this point it was super cold out, and I thought maybe the fuel filter element was wet and icing, so I replaced it . That didn't help so it wasn't that, next was a hard start. Like no fuel, so I thought maybe I wrecked an olive or o-ring installing the filter, tightened and replaced one bad set of return rings, not any better. So next I installed a primer bulb, so if it were leaking back I could prime it. Well the bulb was between the lift and the filter housing, and it still was running poorly and getting worse. Now it was violently bucking like a rodeo bull under load especially in 4th between 1200 - 1600 rpm, buck the truck, surge then stall. I noticed the bulb was collapsing while running, so I thought the lift was weak and pulling a vacuum from the ip pump. So I installed an electric fuel pump and bypassed the mech unit, still same symptoms. Next I blew through the supply fuel line with compressed air, checked the return check valve and elbow (clean) now the primer bulb seems to fill slowly and not collapse, so I think there was a restriction, but the symptoms persist and getting worse. It's no longer drivable, surging and stalling. Idle jumps rapidly between 500 and 1200 rpm. Please offer suggestions esp. if you've experienced this. Next idea is installing a fuel pressure gauge and clear line at the pump to look for air. I'm thinking perhaps an air leak or blockage, does this sound right? Maybe in the pickup? Doesn't seem to change with fuel capacity .. Maybe a failing ip though as well, or maybe internal swelling of a fuel line . I need some advice as I have never had a fuel problem before. Thanks, Leroy

 

Disconnect the supply line to the diesel filter head. Connect a section of hose from that line to a bucket. Power on your e-pump. If you get a decent flow of diesel to the bucket, then your fuel lines are likely not restricted. if it trickles out, then you have some clogged fuel pickup in the tank or in the lines somewhere.

My initial reaction if fuel restriction or air intrusion. It'll surge if you get air in the lines, or if you don't have enough fuel getting to the IP. I had the same issues when my van was surging, so I installed a mechanical fuel pressure gauge tee'd in right before the inlet of my IP. Turned out while idling, I had about 3psi, but once I put load on it, it would dip below 0psi. If I drove it for too long with 0psi, the reservoir in the IP would drain, and then the engine would surge when no fuel was pushed to the injectors.

I'd suspect that you have air in your injector lines, and you will only be able to work that out once you fix your fuel pressure/obstructoin issues, and once you crack the lines to bleed the air out. but first, determine if you are getting solid pressure to the IP and diesel filter.

 

Thanks for the suggestions, I appreciate wisdom of having had these issues and what to look for. I think your probably right, in consultation with the manual - it is showing 4 probably causes . line obstruction inlet, obstruction return, air in lines, or metering valve sticking ( check governer springs for binding, debris, spring damage ) I will put a gauge and clear hose on there to determine if it's the first three. Does anyone know what size the fuel olives are on the 6.9? And how do i remove and reinstall the top plate on the ip, i remember something like runaway if something isn't done in sequence, thanks !

 

I did a quick search and from what I gather the 6.9 uses both sizes like the 7.3? My Ford parts website updated and I can't find anything anymore, and can only get partial #'s. If the 6.9 does use both, then the big ones (3/8 I think) are partial # 9C387 and the smaller ones (5/16) are partial # 9K260. Sorry I can't say for sure!

 

Okay i'll grab a handfull of each those, i got some clear hose - but ran clean out of motivation to put a piece on and blow out the return line .. I hope to get to it tommorow, i really want to know exactly what's going on . i don't know if i'm hoping to see air or not. If there's air - then i know it's just a leak .. But then, i have a leak to chase down .. But i hava a hunch it might be a governor spring too .. I don't know, find out when i get time and daylight i guess, thanks for the olive part #'s

 

Okay, so an update .. I got it *fixed* well what i did was clear out the fuel return line, having previously blown out with air the supply side .. While removing the return fuel elbow off the ip, i noticed both nuts securing the shutoff solonoid and advance were loose (the culprit?) tightened them snug, reattached the return, and put clear tube between the prime bulb and filter head .. Started it and now she's running *good* ..

I say *good* because i can feel this chinsy 1-4 psi holley electric pump is starving the pump .. It's running slow and pulsing with the rythim of the cheap pump, but is otherwise running well ..

Now i'm ordering a delphi mechanical and will plumb a parallel checked fuel line and run off a new known good mechanical and keep the electric as a redundacy - primer pump ..

I did notice alot of air, esp at startup from blowing out the lines, but she never skipped a beat, just ate them bubbles, even when i tried to stall it by turning the primer bulb to suck a chunk of straight air .. I can't imagine but it must take a tonne of air to be causing intrusion issues once it's running, i have a small steady stream of little bubles now that she's run a few minutes, but i'm sure it's not an air problem .. I think it was my shutoff solonoid rattling loose on the ip, if you have running issues, do check and tighten the spade connector nuts on the ip ..

 

Good to hear! Another thing to check for when troubleshooting, never would have thought of them coming loose. Just from vibration eh?

 

Yea it probably rattled loose, though i'm not ruling out an intermitantly failing fuel pump, and sometime i'll have to drop the tanks to clear out the crud that just has to be built up in there.

 

Hi .. Okay, So maybe it's not yet all the way fixed .. I installed a new delphi lift pump, ensured no air troubles, and it is running pretty decent, but not right 100% ..

I took off the top cover of the ip and sprayed carb cleaner on the metering valve and lubed the area with penetrating oil .. While in there i was looking especially at the governor linkage and noticed what I think to be a problem .

I'd like to ask one of yall with a pump you can open up to see if this is normal, i have a hunch it is not ..

The governor pivot arm is pinned on the pass. side but the drivers side of the pivot shaft is not riding on anything, the fulcrum can easily shift to make the governor linkage ride on the pump housing.

I will attempt to show a pic here of what i'm describing .. It is a black "A" shaped governor arm that applies pressure to the spring ..

Mine is secure on the p side but when i push it left there seems nothing is holding that side and the linkage and idle spring go all the way to the housing .. Does yours do this?

Looking at the parts diagram it shows this arm riding on the , governor pivot shaft. I think my gps might have broken allowing my linkage to ride against the cover and result in odd surging and poor governing action .
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a vague reference to a broken shaft indicates that this can be pushed out of the housing, the new part sliding into the gov arm as the old one goes out the other side, has anyone done this? If so, what is the recommended proceedure.

Thanks , if the pics load i will show the gov arm .. Front of the pump

And the exploded parts view, #13 unpinned on one side, and #42 likely broken governor shaft ..

 

Shifty gov. Arm > far left (front)

 

Here's a better pic of the governor arm and pivot shaft .

 

It looks like maybe ? I could install a new arm from the top? If it turns out the arm itself has worn through, i think i will order both the arm, shaft, and nut seals.

Any input of how to get these in-out is much appreciated .

 

Sometimes you feel like a nut .. Maybe remove this and slide shaft ( 1/2 of it?) out .. Pull arm and reverse to reinstall .. ?

 

I found another db2 manual, this shows things a little more clearly .. It looks like there are nuts either side retaining the governor shaft, i'll take out the top springs and linkage, remove both nuts .. Push out the old shaft(s) drop a new gov. arm in then reinstall a new shaft.

That's the plan anyway

 

Just by looking at this illustration, that governor arm isn't suppost to have that much play .