Weird Airlock Issue-Injector line not purging

[BrentN]

Short Background Story-
Had really filthy main fuel filter. Changed
Just changed out the sock in the tank..It was filthy too.
Cleaned the tank.
Clean fuel in tank
Purged the air out of the filter housing.
Purged the air out of the T-handle

When I start the engine with foot on throttle, engine will go to 1500-2000 and then fall off.
Idle is about 600 and engine is not smooth.

I have cracked (to bleed) 6 of the 8 lines (2 under the turbo are left alone) and cranked several times.

Engine behaves in pretty much the manner while running, rough and it really wont respond to large throttle inputs. Only a light foot and it will struggle getting up to 12-1500 rpm

After several rounds of doing this, I started and let it run for a whle.

Now when I crack open #1 injector line while the engine is running, I am not getting any fuel out of it. I had earlier, the head has fuel on it below the injector.

Does anyone know how come the injector pump isnt purging the line? Could the pump be more airlocked than normal? Do I have a pump issue? Do I need to pull the top of the pump?

I havent checked any of the other lines to see if they arent spitting fuel.

The engine is running like it is missing 1 to 2 cylinders right now.

Appreciate your help in advance.
Thanks,

[BrentN]

Things are a bit better this evening.

I went back out this evening and restarted it. Was able to get the rpm to get above 2000 after some coaxing. Opened #1 and was eventually able to get fuel to start spitting out of it.

Let it run for quite awhile, cycling the rpm. Eventually it would pop above 3k. My Service engine soon lite had come on while cyclng the rpm.

Will wait and see if it the code drops off once the engine cools through the 3 cycles to reset codes. If not, I will go to Autozone and have them pull the codes. It may have detected the miss or seeing something wrong in the Inj Pump.

I ran it up to about 60mph and drove around. It still seems a bit sluggish on acceleration. Runs out of juice above 60.

I had put an aftermarket (NAPA) lift pump in (before I realized my filter was completely plugged). I may put my GM pump back in tomorrow- it just seems like it is running out of fuel.

I will keep everyone posted. As always, if anyone has there $.02 worth or have seen this before, would love to hear from you.

[BrentN]

Success at eliminating fuel starvation, air locking issues.

After replacing the Main filter twice and still having severe driveability problems. The next steps were:

1. Drop and Clean Tank- Sock was plugged. Replaced with AC Delco Sock
Results- No major imrovement, but needed to be done. Still no power and fishbiting at speed or some throttle.
Trouble bleeding injector lines- couldnt get them to bleed.
Ran like crap, but finally bled out, but idle still wasnt smooth. Never have had that kind of problem bleeding before.
During this time, the throttle really didnt respond very well.

2. Replaced Napa Lift Pump with AC Delco from Kennedy. Pump was quite a bit noiser than the OEM pump.
Blew the line with air back to the tank for good measure.
Results-Minor Improvement. Pressure went from 4psi to 7 psi. Could drive around town, but no load or heavy accel.
Can get to 65mph but it is slow and lacks power. Fishbiting above 65 mph.
Still wouldnt take it on a long drive or put a load to it.

3. The Final Item- The inline filter/strainer on the inlet of the Injection pump.
Inline filter was plugged badly, had black sludge in it. Cleaned it well with water and the kitchen sprayer.
Have pictures attached. The first 2 are the gunky filter. The 3rd and 4th are the clean filter.
There is a little cup mesh filter at the bottom of the inlet cartridge. Removed and cleaned it.
There is a pressure plunger on that end. Make sure you push it in and clean well.

Results- Great Throttle response- No Fishbiting. Problem resolved.

Final comment:
Got a really bad load of fuel. Plugged all the filters. Likely the lift pump was dying or died. It was the original. The Napa pump may be an ok backup-had it in my garage for years, but firm believer in the AC pump. Based on the dirty fuel and the age of the truck, I would recommend everyone take a look at their injection pump in-line strainer and clean it out.

I appreciate everyones help and the side conversations we had.

[sctrailrider]

Glad to see that you were able to find all the little filters to clean, most people don't check the last one in the IP.

[arveetek]

Thanks for posting up what you found! I may need to check that screen in my IP as well. I still get a slight hesitation and fishbite when under load sometimes.

Casey

[BrentN]

Its really nice to have this one licked. I even drove 120 miles on the freeway yesterday (with steep hills), with a trailer on and NO ISSUES.
I was beginning to wonder. Non simple solutions coming to mind like: Injection Pump Failure or Injection Timing were coming to mind.

But alas, always start with simplest thing first.

It was Robyn that pointed me to the in-line filter in the Injection Pump. Thanks Robyn!!

Now I can get back to the other automotive projects on the Docket:
Finish the head gasket job on the $700 1989 Toyota Tercel that we bought for our son.
Oil Changes and all of the other maintenance for the Automotive herd I have. At least old reliable, the Suburban, is back in the "old reliable" category.