New lift pump, higher EGTs...

[pnishr]

(SHORT SUMMARY AT BOTTOM FOR THE ATTENTION DISABLED)

So, over the weekend, I was going to use my truck to move a couch...

It had been a little harder to start the last few times I drove it, so I figured it was a fuel-line leak letting the fuel bleed back. Because it was easier to start after it had been running a while, and the longer it sat, the harder it was to start.

Well, Saturday when I wanted to move the couch, it wouldn't start at all. It was cranking and puffing out a little smoke. But it just wouldn't start. Based on my research here, I decided it was a lift pump issue. Fortunately, I had already bought the part and just hadn't installed it.

So I install a mechanical lift pump and use an electric auxillary pump to prime the lines. I also changed most of the rubber fuel lines (I tried and tried, but couldn't get that stupid clamp off of the IP) and the fuel filter. The truck fires up and runs normal. I turn it off and let it sit a couple of hours. Then start it up again. It fires right up again and is running just fine. Turn it off.

I load up the couch, start up the truck and drive it to the fiancee's house (30 min). Unload the truck, then drive it home. I'm about 15min into the drive home and it starts acting weird.

It seemed to lose power suddenly when going up a hill. I thought maybe I had done something stupid and left a hose unclamped and it was losing fuel. But it kept running. And, rather than act like it wasn't getting enough fuel, it was acting like it was getting too much. My EGTs were higher than normal. (by about 100-200 degrees).

As soon as I got off the highway near my home, it began to act somewhat normal.

Important to note: I have turned up my IP by about 1/6 turn.

SUMMARY: I have the IP turned up 1/6 turn. I almost never let it go above 800*. Cruising EGTon the highway was typically 400-600*. Replaced the lift pump. Ran like normal. All the sudden, lost power and cruising temp on the highway went up to 600-750* (so I slowed down to keep EGTs down)

Could the new lift pump have caused this?

If so, why did it take me driving over 45min for the problem to arise. And why did it happen so suddenly?

Any input is appreciated.

 

[Chaski]

Lift pump pressure can affect timing advance. What kind of electric pump did you put In?

 

[pnishr]

Hmm... Well, I put in a basic Mr.Gasket 12D pump just to prime/bleed the lines, but it wasn't doing the pumping while I was driving. I was driving off the mechanical lift pump. It's the recommended NAPA one.

How/why would the advance change so suddenly after 45min of highway driving?

I'm starting to think maybe I got a plastic trash bag sucked into/covering the intake while on the highway. But when I popped the hood when I got home I didn't see one. (although, I didn't have time to inspect/take off the cover).

I may head over and check it tonight and see if it's still firing up/running normal, as well as pop the intake cover off.

 

[Chaski]

I'm out of ideas.

Injection pumps are full of urethane and rubber bits that don't last forever, and the advance piston in the bottom is steel moving in an aluminum bore which wears over time. You can often take a look at the top of your pump and see if has been refurbished in its life by one easy to spot feature. If the pump was gone through sometime in it's life and had the governor weight retainer replaced with the newer style that does not have a urethane ring it will have a little aluminum tag with the letter "E" stamped on it. The tag will be under one of the screws that holds the lid on.

I'm curious what it turns out to be.