ytudrepus

Any engine builders out there seen this before?

Rebuild my 95 5.0L (and tranny), new pistons/rings/bearings (old cam/valve train with the except of new springs). Found crack between the valves used some junk head heads, same casting number - shop did new seats/guides.

Truck has no vacuum (5 at idle, maybe 9 at 3500), can't drive the truck up the driveway (...no go).

compression check=140 - 150 across all cylinders
Leakdown test = only slight noise in oil filler (assume rings not seated), noting in intake or exhaust).

Truck starts right up and idles fine (no codes), TPS is good (if I did the check right), tried propane for vacuum leaks - no noticeable change in engine idle. Checked all the vacuum lines (plugged the coffee can line).

Had a shop check the upper & lower intakes and heads for warp, they said they were flat and no signs of machining.

I'm stumped. taking the valve covers off to install the old springs (out of desperation...).

Thoughts?

ytudrepus

Oh, I did change the timing chain too (while checking the valve timing the chain was right at the max deflection), so before/after new timing chain no change.

ytudrepus

So, the truck sat for seven months (over the winter) while I rebuilt the tranny and engine.

I cannot locate the problem of this low vacuum, I'm wondering what I could have put together wrong that is causing this problem. (in full disclosure "DA" my trusty alter-ego did overlook the oil plug on the top/rear of the block...that was the first of many times the lower intake has come off)

Is it possible I need the computer reflashed? (from sitting so long)

GhostriderI

What year is the truck? Did you delete/bypass any of the vacuum system?

ytudrepus

Maybe a description of how the truck is operating might help.

Starts right up and idles fine, is slow on the rev-up (only run to 3500, but takes a good second or two (I'd describe it as a turbo lag type of climb))

Put the truck in drive 9/10's of the throttle movement the truck feels like its trying to pull some super-massive load, only creeps (maybe 2 or 3 MPH), the last 1/10 of the throttle (WOT) RPMs slowly climb to 3000 - the truck accelerates at an equally sluggish pace (takes the whole block to reach 25 MPH), shifts into second (kicks like a mule - I did the J Mod on the tranny).

Does not have enough power to accelerate in second gear, basically crawls along "bogged down" in second with high RPM.

I've thought maybe I did something with the tranny, but it appears to be running fine, and the tranny doesn't explain the low vacuum at idle.

ytudrepus

GhostriderI,
1995 F150 - the only mod to engine from stock was I made a blank off plate for the EGR.

I've blocked "coffe can", brake booster, and crankcase vent (wasn't really sure which of the smaller lines I eliminate).

ytudrepus

I did reinstall the original valve springs, the summit springs are 1/8 taller than the exhaust and when I bought them I was told "one size fits all".

Truck runs (crappy - doesn't idle as nice) the problem continues.

GhostriderI

I would double check the block off plate for the EGR and you might have missed a port on the intake, also, did the fuel you are using sit in the tank while the truck was down? (Poss sludge on pickup tube) Have you checked/changes the fuel filter? Checked fuel pressure at the rail (I think >30 caused issues should read 35 to 45psi) poss FPR going bad or weak pump

Hope this helps

ytudrepus

Yea, the truck has dual tanks I put fresh fuel in the empty tank, I changed the inline fuel filter and checked fuel pressure (although that was back in the spring and I don't recall the number, only it was good).

I can do it again, I'll check the blank off plate.

ytudrepus

fuel press, 40 psi at start when cold, once the engine warms up the pressure drops to about 35, when I pull the vacuum line from the regulator psi jumps to 41.