Need some IDI help

[Bean]

Got a 7.3 van here that we put in a Hmax turbo, injectors and IP all at the same time. I have it timed the best I can to 8.5 deg BTDC. Problem is it has a lope to it and smoke bad when cold and overall just isnt right. Its real hard to time cause any timming light I use it jumps all over and hard to figure out where it wants to be. I am using the Mac timming tool with a mac timming light adjusted to 8.5 deg advance. When the rpms are up the engine is smooth but not much power and no smoke and teh pump is supposed to be turned up and I turned the fuel screw a hair before installing it.

Any ideas?

 

[towcat]

I would suspect the pump may be in the need of a rebuild or a injector is hanging.

 

[Agnem]

If your timing light is jumping around, then there isn't much guarantee that you have it timed to where you think it should be. Don't forget that 8.5 degrees requires a 20 degree offset. If you have it static timed (marks aligned) does it still lope? When you removed the IP, did you do it correctly, or did you make the common boo boo of taking the IP gear cover off? Assuming it IS in time, then I would look towards a bad injector. Were they tested before being installed? Sounds like your saying you put all new stuff in, but new stuff has been known to be bad now and then, so testing is the best way to be sure.

 

[Bean]

Yes it was all new injectors and reman pump. I did pull the cover but marked the position of the dowel pin on the cover before taking it off, being on a van the easiest thing to do was pull the cover with the pump and do everything on the bench then reinstall with the cover attached to the pump, realigned dowel pin to the mark I made (12:00 position) and bolted it back down. It does get better the more I advance it but never smooths out and will keep puffing some slight smoke as it lopes. Not sure on the static time cause I need a mirror to see it and havent tried to look, I hate vans.


Now the 20deg thing I didnt know, will redo that. wierd thing is moving the dial on the light didnt seem to change the position of the mark much at all, so I have a new light on the way. Still dont know why it jumps so much either, at around 2k rpms the engine is smooth but the pulse is not smooth from the light.

 

[77f250diesel]

Mel--Could you explain the 20deg. offset ?

 

[Agnem]

The scribe on the harmonic balancer is 20 degrees BTDC offset from TDC, so meters need to take that into account when doing timing measurements. OK, I feel your pain on the van. What about the injectors?

 

[Bean]

The injectors are brand new stanadyne flavor. Still dont know why the pulse is jumping all over. You can see it in the little led light on the pulse adapter too, you can see the intermitent pause on a regular rythem. I should have my new didgital timming light on Wednesday and see what it does with that.

So I should set the light to 28.5 then to line the marks up?

 

[Black dawg]

sometimes you have to move the pulse adapter and retighten, if it is loose it will act like this. now as to the offset, just set the light at 8.5 or where ever you want it and turn the pump till the marks line up. with a turbo and a healthy fuel rate they seem to run better and have less black smoke at 5-6 degrees.

 

[Agnem]

I've never used a timing light to do this, so I'm not sure how you deal with the offset. You say the injectors are new, but you still haven't said if you tested them. If they aren't tested, then everything you do is just guess work.

 

[77f250diesel]

Bean--My old timing lite acted the same way. Also make sure your as close to the injector as possible [an inch or two from the elbow to the injector] and the ground should be abt. 4 inches away on the same inj. line. Inj. line has to be clean ! Use sandpaper and get nice clean metal showing. When you get your new lite look at the inductive p.u. for an arrow which would normally point to the spark plug--that's important which way it points on the "loop". I have my timing set at 3-4 deg. btdc at 1400 rpm and it starts and runs good.

 

[Bean]

Ok, got her all to work good and the timming is real close, close enough that I know thats not my problem now. I did not test the injectors before I put them in, got them from one of my suppliers that do pump rebuilds and other fuel stuff so I assumed they would be drop in ready.

One thing I have noticed is lots of air in the fuel when breaking loose a injetcor line, get lots of air bubbles out it. It also takes a few cranks to get it to fire when cold but not a ton and it idles the worst when cold when it gets warm it idles pretty good but not perfect.

Would the return line routing make a difference? I can not find any leaks anywhere in the returns or feed and I have an electric lift pump on it to supply pressure at all times.

 

[apextrans]

I did pull the cover but marked the position of the dowel pin on the cover before taking it off, being on a van the easiest thing to do was pull the cover with the pump and do everything on the bench then reinstall with the cover attached to the pump, realigned dowel pin to the mark I made (12:00 position) and bolted it back down.

I just made this mistake myself. Pulled my cover & gear not realizing it was indexed. I was told that even being one tooth off with the timing gear could result in a no start or rough running. Maybe everything else is OK & your off by a tooth or two?