7.3 Misfire? Pump Timing? Fuel Issue? shaking HELP

[7.3 Sloth]

1988 f350 7.3 idi. So im having trouble figuring out my missing or chuff issue. i cracked all 8 injector lines and all appear to be doing their job. I just dont know how well. Could it be a weak IP or can it be bad injectors still? Possible valve issue? i compare my truck to my buddies 90 f350 idi and his sounds alot smoother running and feels smoother. I have my muffler off as i am installing a stack. And the miss is more noticable now obviously louder. It sounds like a john deere A. Return lines are all wet and i noticed after cracking injector lines the fuel that rested at the bottom of the injector started bubbling. On all of them. So i have a feeling air is getting in too. Engine has 200k+ and injectors and pump seemed like they were never replaced. Should i overhaul the fuel system, new pump, injectors etc...? Or take the valve cover off and see if something is wrong under there? any advice or suggestions are welcome. thanks.

 

[Clb]

A quick search will give this answer!
At 100k you need new pump/ inj.'s
At 200k its a good bet!
Go do some reading in the stickies!
Look at the idi tech section!

 

[franklin2]

A compression check will tell you the mechanical condition of the engine. Then you can go from there with injectors and IP if that tests good.

 

[OLDBULL8]

Return lines are all wet and i noticed after cracking injector lines the fuel that rested at the bottom of the injector started bubbling. On all of them. So i have a feeling air is getting in too.

You certainly do have air intrusion, with the engine running and your getting what you say above, check all your rubber lines from tank to lift pump for cracks, if original, replace them, use only diesel rated hose, check the Olive seals on the steel lines, one seal on top from the lift pump to filter, two seals from filter to IP. Get a return line kit and replace them, kits from Typ4 or Agnem, ebay usually are crap. Air (bubbling) coming back up the injector, indicates the pintles are not sealing, new injectors are needed, get them from typ4 or Agnem, ebay rebuilt injectors are mostly crap, but your choice, read the Hall of shame thread first. Your choice on the IP as to whether you need a rebuilt one, get from same people. Some one has a Moose IP in the Marketplace forum, check there first. New Stanadyne IP's are not available anymore IIRC.

You can PM Typ4 or Agnem, Agnem ownes www.conestogadieselinjection.com --check him out.

 

[towcat]

rule of thumb. may not apply all the time but when I am at an auction, there is no way in hell they will let me tear apart a motor......
rough idle....could be air intrusion, pump or injectiors.
rev it up and things get alot worse......ie. lotsa smoke, really bad miss and getting worse as it's being rev'd...BAD PUMP
rev it up and things smooth out ........bad injectors.
rev it up and misfire does not change consistency.....possible bad hole...remove oil filler cap and observe blow by output. if smoke is consistent with misfire, you have a bad hole.
I've bought and sold many trucks through the auction. When buying, I look for the problem children that others are scared to bid on and I bid accordingly to my findings.

 

[7.3 Sloth]

Thanks for the replies. I'm most likely going to overhaul the entire fuel system as my truck still needs a considerable amount of work. It revs up and smoothes out but idle is terrible. I got this truck last year and never really did anything to it. Only now realizing all of what it needs. It only smokes when cold. No excessive smoke warm. I appreciate all of your inputs and fast replies. I'll look into those guys for my parts.

 

[towcat]

Thanks for the replies. I'm most likely going to overhaul the entire fuel system as my truck still needs a considerable amount of work. It revs up and smoothes out but idle is terrible. I got this truck last year and never really did anything to it. Only now realizing all of what it needs. It only smokes when cold. No excessive smoke warm. I appreciate all of your inputs and fast replies. I'll look into those guys for my parts.

if you have any friends with a set of good used injectors, throw them in before your rings are fubared. hell, it's only a return line kit at worst. of crack the lines and see which one is lazy and change that one out.

 

[gandalf]

... I'm most likely going to overhaul the entire fuel system ...

Read Mel's Article before you start working on the fuel system. This is the information we have grown to trust. Mel, BTW, owns and operates Conestoga Diesel, mentioned earlier in this thread.

 

[Agnem]

I wrote this to help people understand another aspect of going about replacing or upgrading a fuel system... http://conestogadiesel.com/support/fuelinjectionservicingadvice.html