6.9 IDI shuddering, low power, new filter, IP and injectors

[Jmackk]

Hey guys,

I have an 86 F250 6.9 IDI ATS turbo, manual glow plugs, C6, 4x4, strait piped, that I have been working on it for a few months and finally have it on the road. But know that its on the road when it gets up to temp it shudders at idle(at stop light) and acts like it wants to stall, it also has a "lopping" sound coming from the exhaust like when you would cam a big block, that "dud duda da dud da duddud da " sound. I have read a lot bout IPs going out or bad injectors and such but the IP, injectors and fuel filter are all new(less than 30 mile on all of them). The fuel in the tanks is old but I have mixed in new diesel and diesel clean additives but Im wondering if it would still be enough to clog the filter and or IP. It blows black smoke but also some white as well. Is it being over fueled or under fueled or????? It fires right up within 2 cranks and has fresh glowplug's.

Also, I read that this year truck was only offered in 4.10 and 3.73 gearing, and I have 3.51 gearing in mine(been re-geared) and im wondering if that is why the truck seems to be lacking power. I know these trucks were not power houses but I feel like I have a V6 under the hood lol I thought the turbo was supposed to "wake up the beast" lol so im thinking I may have other problems some were.

Any and all help is needed, thanks guys

 

[Kevin 007]

Almost certainly an air intrusion issue. Im on the road and don't have time to elaborate; but im sure someone will shortly. Could very well be a broken pick up tube in the tank to leaky injector return lines and olives etc...

 

[Wyreth]

It does sound like air intrusion. However the loping makes me wonder about a burned valve. Some things I would try:

Put some clear line between your lift pump and filter head, run it and watch for air bubbles.
Compression and leakdown test it. (if you don't have a leakdown tester, you can just blow compressed air down the GP hole. Make sure you get an airgun that has a rubber tip on it so it seals. If you hear air out the tailpipe, you're gunna be pulling the head.)
Get a timing meter (buy one, or rent one from Gary) don't just time it, but also take readings from different rpm points. Shut it down, then re-test at those same rpm points. Just because it's a new IP does not automatically mean it's good.

 

[f-two-fiddy]

Hey guys,

I have an 86 F250 6.9 IDI ATS turbo, manual glow plugs, C6, 4x4, strait piped, that I have been working on it for a few months and finally have it on the road. But know that its on the road when it gets up to temp it shudders at idle(at stop light) and acts like it wants to stall, it also has a "lopping" sound coming from the exhaust like when you would cam a big block, that "dud duda da dud da duddud da " sound. I have read a lot bout IPs going out or bad injectors and such but the IP, injectors and fuel filter are all new(less than 30 mile on all of them). The fuel in the tanks is old but I have mixed in new diesel and diesel clean additives but Im wondering if it would still be enough to clog the filter and or IP. It blows black smoke but also some white as well. Is it being over fueled or under fueled or????? It fires right up within 2 cranks and has fresh glowplug's.

Also, I read that this year truck was only offered in 4.10 and 3.73 gearing, and I have 3.51 gearing in mine(been re-geared) and im wondering if that is why the truck seems to be lacking power. I know these trucks were not power houses but I feel like I have a V6 under the hood lol I thought the turbo was supposed to "wake up the beast" lol so im thinking I may have other problems some were.

Any and all help is needed, thanks guys

That right there tells that it's prolly not air intrusion. Where'd you get the IP from? How long was the truck sitting?

 

[hesutton]

Ford didn't offere these IDI's with 3.73 gearing from the factory. 4.10 or 3.55's are the factory ratios.

Like asked earlier, who rebuilt your IP and are the injectors new or rebuilt? How old was the fuel? Did you put any biocide in the fuel. Algae can be a real bear to deal with in the fuel system. The "hunting idle" or "lope" can certainly be air intrusion into the IP. I could also be an issue with IP itself. The fact that it only happens when the IP is warm is a concern that there are some tolerance/clearence issuses with the IP. Again, I know this is something that Mel has mentioned in the past. Even if the IP is "newly rebuilt", if somethings were overlooked during the rebuild, it still can be a source of problems. The shutter at idle could also be a few leaking injectors (white smoke too). IP timing is important for quality performance and that certainly could be another soruce of lack luster power.

Heath

 

[Jmackk]

Ok guys sorry for the delay, the IP is a Pensicola pump, truck was sitting for almost 2 years and I have been re-sealing and rebuilding thing one by one and changing fluids and suck. But I have since found out the problem. The pickup in the front fuel tank is toast. I was actually driving home from work and the truck died on me on the way home and would not start. I was running on the front tank and I had half a tank of fuel and could not get it to start. I cranked on it on the side of the road for prob 5 min and no start(not 5 min strait lol). I figured as a last ditch effort to try switching tanks and when I did she fire right up. And has run fantastic since. I dropped the front tank last night and the picked was......basicly non-excistant. So for know I'm down to the back tank only till parts come in for the front tank and I might as well do them both. But I seem to have the power back and it idles smooth and actually is not smoking as bad either so I'm glad it's not burnt valves or anything like that.

 

[Jmackk]

And injectors are new not rebuild

 

[icanfixall]

Well... It was an air intrusion problem.... Caused by a bad front tank pickup. A length of fuel rated hose and a clamp will fix that and do it on the cheap... Sorry to dropped the front tank because you can reach the fuel pickup and sender unit with out dropping it... The back is differant. Dropp the tank or pull the bed off.

 

[Jmackk]

Ya I started to drop the tank and stopped, I decided it would be easyer to pull the bed, which I did but I pulled the tank after any way. I figured I might as well clean it out. And sorry about the bad grammar last post I was distracted