Idle Pump Timing

I owned the '90(sig photo) prior to, and 4 additional IDI's since joining this group 12.5 years ago. I've never had to mess with the injection pumps or pump timing. I recently finished up head gaskets on the '93 w/Banks Sidewinder I picked up in August. The PO was a lady who's estranged husband had clearly done a fair amount of tinkering around under the hood. She couldn't provide a lot of color on the history other than he jacked up the glow plug relay wiring(beyond recognition and usefulness), and as a result of starting fluid, the head gasket(s) as well. She ran him off and the truck set for and extended period of time. When I put the injection pump back on, the static timing marks were aligned. I felt like this was a good place to start considering the unknowns.

When I got it running, it idled very smooth, but poured a ton of gray smoke. An intolerable amount. When warmed up, it stalled when returning to idle after revving. I advanced the timing from static, and I feel the smoking improved (small but noticeable), the idle remains smooth, and the stalling condition seems to have gotten better, but black smoke rolls with any revving and it seems grossly under powered. I've done a lot of research and reread threads addressing pump timing. While there is a lot said about pump timing and exhaust smoking, there aren't many remarks regarding pump timing and idle quality. What is the window between pump timing advance and retard where idle quality remains generally unchanged? I'm feeling like I need to baseline some variables in attempt to find a quality starting point on the timing. Some will say that the pump must be timed properly first, but I'd like to make sure the fuel screw and other factors are normalized first. Someone leaned on the pump timing adjustment boss previously, as part of it is fractured off, making it difficult to adjust the timing.

Thanks in advance for responses.

I'm absolutely not the expert here, but my gut tells me you are barking up the wrong tree.

I suspect the guy turned the fuel up, on the Injector pump.

Turning the fuel up, would cause the black smoke.

Too much fuel would also cause white smoke, if the IP timing were not also advanced.

My suggestion would be that you turn the fuel down by a flat or two.

Do one flat at a time, until you get rid of the black smoke.

And then you can look at the Timing.

I'm the opposite, I would start with timing.
Is it possible you got the gear timing to the ip off?

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79jasper said:

I'm the opposite, I would start with timing.
Is it possible you got the gear timing to the ip off?

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He already started with timing.

79jasper said:

I'm the opposite, I would start with timing.

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Me too.

Selahdoor said:

He already started with timing.

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I would continue on with the timing. Too much advance or retard of the timing can produce the black smoke. I'd say to advance the timing some more before you mess with the fuel settings. The original excessive smoking and the stalling issue, both of which improved some after the timing advance, sound like timing to me. Also, the fact that it's very underpowered also makes me lean toward timing.

All good points.

What happens with too much fuel? Black smoke.

Retarded timing will cause the white smoke. (And no black smoke. That was my own experience. Very retarded timing resulted in loping, rough idle, no power, wanted to die when the go pedal was let loose of, and white smoke all the time. Never had any black smoke because of it.)

His problem was the white smoke, (Grey), and black smoke. Both.

I think this means his timing might have needed advancing, absolutely. But the fact that there was already black smoke, even though the timing was retarded, makes me think the PO turned the fuel up. (Probably intentionally to make that black smoke.) But never turned the timing up.

The pump on my first 85 F250 had God only knows how many miles on it. At first, it was ok in the smoke department. As time went on, it started smoking worse and worse. I turned the fuel down a couple of times. The only reason that I can think that I didn't try advancing the timing, is that this was during my heaviest period of drinking and I probably wasn't thinking right. It never did have any color of smoke besides black. How old is the pump? How many miles are on it? How far past the factory lines was it advanced? Only work on one thing at a time. If you play with both the timing and fuel settings, then you won't have any idea of what adjustment did what? Get it running right first. Then think about fuel settings.

Retarded timing at idle makes white smoke, but at wot can make more black smoke than the same fuel quantity with more advanced timing.

From what it sounds like, the advance piston is gummed up and seized, giving you the smoke at idle which mechanically advancing the pump helped masked, but does nothing to fix the issue with the hydraulic advance in the pump which is malfunctioning. Run some heavy fuel cleaned like hotshots diesel extreme or try filling the pump with atf and letting it set, you may be able to free up the piston but expect a pump rebuild in your future.

Thewespaul said:

but expect a pump rebuild in your future.

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Also part of the reason I asked about the condition of the pump. If it has a lot of miles on it, no amount of adjusting will make it run right.

I don't think it would start and idle as well as it does now if the drive gear jumped a tooth off in either direction. Everything, including the pump dowel lined up during assembly, just as it was when disassembled. It sounds great and idles very smoothly. I don't know which direction to go with the pump timing to resolve the conditions I'm experiencing, and my gut is telling me that timing the pump is not the issue. So, I'm wondering how far advanced or retarded must the pump be to alter idle quality. This would give me which direction I need to go.

Do

79GLIDE said:

I don't think it would start and idle as well as it does now if the drive gear jumped a tooth off in either direction. Everything, including the pump dowel lined up during assembly, just as it was when disassembled. It sounds great and idles very smoothly. I don't know which direction to go with the pump timing to resolve the conditions I'm experiencing, and my gut is telling me that timing the pump is not the issue. So, I'm wondering how far advanced or retarded must the pump be to alter idle quality. This would give me which direction I need to go.

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Don't dismiss the advice to try and clean the pump out. Take the fuel filter off, pour out the fuel and fill it back up with atf. Get it started, run it for a minute or so, and then shut it off and let it sit for a day or two.

I do have a new Wix separator filter I paid a premium for at the local O'Reilly's. I think I've got either 911 or Diesel Kleen and ATF in the shop. I was thinking about returning the filter until I get these other things figured out, and using the existing filter for the cleaning process. The rear tank sat full since the head gasket went, so that's the one I'm running off of. The front tank is nearly empty, so I could juice it up with some concentrated fuel and cleaners. I don't think anyone within 100 miles of me has dynamic timed an IDI for several years.

Would the gear timing to the IP cause a lack of power ? My 94 ran great until I had a lot of work and upgrades done to it, now it starts fine but just wont drive over 40-50 MPH.

Alwaysreadyrob said:

Would the gear timing to the IP cause a lack of power ? My 94 ran great until I had a lot of work and upgrades done to it, now it starts fine but just wont drive over 40-50 MPH.

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Yes it can if the IP was removed and replaced 1 tooth off.
Check fuel delivery pressure also.
May also try advancing pump a little.

riphip said:

Yes it can if the IP was removed and replaced 1 tooth off.
Check fuel delivery pressure also.
May also try advancing pump a little.

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So, you're saying that it is realistic that you can get the IP drive gear timing off by 1 tooth in either direction, and still expect reasonably easy starting, smooth idle and have a truck that is driveable, to some degree.