6.9L IP on a 7.3L?

[adamsanders]

So I posted another thread about my hot start issue and it was more or less determined I probably needed an injection pump. So before I spent 500$ on a good rebuilt IP I wanted to try a cheap Craigslist option. I found one for 50$ off of a 6.9L so I bought it. This past weekend I put it on on my 7.3L. I finally got the air bled and the truck started up but smoked white/blue like crazy. Adjusted the timing a little and the smoke basically went away. However the truck still ran poorly. Sounded like it was missing, stumbling, had no power, and didn't wanna idle. My question is do I need to turn the fuel up to compensate for the bigger engine or should I try something else? I have no idea if the pump was any good to begin with but I figured for 50$ it was worth a try. Thanks

 

[Thewespaul]

Craigslist ip is a shot in the dark but you can try to turn it up a flat and see if it changes it any. It's difficult to say if that pump is any good without being able to properly tire the pump but does it behave any different depending on if the engine is cold or hot?

 

[adamsanders]

Not that I can tell. I'll turn it up a flat and see if it changes anything. Could the fuel being low cause that kind of missing behavior?

 

[Hydro-idi]

Sounds like you replaced a junk IP with another junk IP. Going the cheap route will just cause a bigger headache in the long run. If you have the funds, buy a rebuilt IP from Conestoga diesel or Russ aka typ4 and it'll run better than the day it rolled off the assembly line. It's always a good idea to replace injectors at the same time.

 

[bbjordan]

IIRC, there was a question of whether the timing was correct or not. Specifically with regard to the IP pump gear. Check the timing! You are just guessing now.

Check the timing registry on this site. There is probably someone fairly close that can help you out, or keep guessing and throwing parts at it. Your choice.

You might want to get the injectors pop tested too.

 

[Macrobb]

Timing is your problem, that or air getting into the fuel supply.
You don't need to turn the fuel up to get it to run well - it *only* affects maximum power. At worst, currently, you may produce a few less HP at WOT than it could.

Fix the timing/fuel supply issues, get it running well... then adjust the fuel screw to match. Otherwise, you aren't helping anything.

And yes, a 6.9 pump will supply more than enough for a NA 7.3. It'll also do the same job turned-up as a 7.3 stock IP on a turbo motor - it can supply about the same amount of fuel when cranked up.

 

[icanfixall]

You may have issues not mentioned yet. Please don't get your feathers up but "how did you replace the injection pump/". Did you remove the pump, gear and tower as one piece. If so you May have missed a tooth on the injection pump gear to cam gear. Remember this gear is the same size as the cam gear. Its nearly impossible to see the timing marks. The "Y" must match the "Y" on the cam or it out od gear time and wont run well.Sadly these engines can me 180 out of gear time and run fairly ok but no wheres near correct. Thats when the Y" mark is matched up with the DOT mark. I have seen this once run too. Sad part was this engine had the pump replaced by a "shop" that knew what they were doing. Then the owner took it to Diesel Dog Catcher and we talked thru the problem but he was the wrench that fixed it. Ron is the bright crayon in the box...

 

[adamsanders]

Thanks for the input. I did change the IP using the correct method listed on this site (left gear housing attached). While the pump was off I rotated the engine around by hand until the crank was at TDC and the dowel pin on the gear was indeed around 4 o clock. I suppose it could be 180 out because I didn't check compression or exhaust stroke. However, with the other pump it did run very well, just wouldn't start when hot. So I don't believe it is 180 out, but I can check for sure. As far as other factors not mentioned, what could I look for specifically? The pump doesn't have any visible leaks and i don't believe I had air intrusion before as it would hit in just seconds after sitting for multiple days.

 

[chris142]

There is only 25 cuin between the 6.9 and 7.3..i'm guessing a pump swap is not your problem.

 

[adamsanders]

Also, is there anything wrong with the pumps from Orieleys, Advance Auto, Rock Auto, etc? I know the Moose pumps and a couple of others mentioned on here are as close to a sure thing as you can get but Im just curious.

 

[chris142]

Also, is there anything wrong with the pumps from Orieleys, Advance Auto, Rock Auto, etc? I know the Moose pumps and a couple of others mentioned on here are as close to a sure thing as you can get but Im just curious.

If they are as bad as their alternators and starters I'd stay away... i'm sure they are rebuilt by the lowest bidder who has probably never even driven idi

 

[IDIBRONCO]

As long as you left the gear cover on, then your gear timing isn't off. The dowel is there to insure that the pump is in time with the gear. It doesn't matter if you rotate the engine or not.

 

[adamsanders]

IDIBRONCO, sorry I should have linked the other thread to this one. The PO said he had taken the gear housing off and he told me he did not know if he had got it back in time. I was just trying to confirm if it was correct or not.

 

[IDIBRONCO]

Well if the dowel is around 4 o'clock, then it's close. That's where it should be. Maybe you can get lucky and use a pick to feel if the Ys are lined up. Yesterday after I pulled my engine out, I got lazy and pulled the whole housing to remove the injector pump. It's ok in my case since I'm going to be installing a Typ4 cam. I was more interested in getting the heads off to check cylinder wear.

 

[Macrobb]

Don't worry about lining it up dot to dot. Just skip it advanced one tooth. That'll fix the problem(symptoms are basically one tooth retarded).
And you may end up, when you take it apart, one tooth advanced. That's OK - I've found a few IPs that "liked" being a tooth advanced. Probably just wear, but they ran just fine that way.