Hey guys I am new here. I have been reading around and trying to figure out what is going on with my new truck and have been driven to the point that I decided I need to register and start asking questions.

I got a 1989 F250 with the 7.3 a couple weeks ago from a guy close by and he basically said it had some air leaks and on cold nights it would be impossible to start the next day unless you cracked the injectors and so on. I read up on it before I bought the truck and thought oh this should not be a problem, I will get this thing fixed right up.

When I drove it home that night on the interstate there was the dreaded jerking when you would let off the pedal in 5th gear sometimes even in 4th. (The previous owner did warn me of this and said it was PROBABLY part of the air intrusion issue but mentioned how cheap new injectors are for the IDI's compared to Powerstroke's) Anyways, I limped it home bucking and jerking even when I had my foot into the pedal (and it wasn't jerking) I could feel the engine missing here and there. The truck was new so I was still figuring it out if you know what I mean.

Fast forward and I have found the fuel heater leaking so I tap and plug that guy off completely. That pretty much fixed the fuel filter leaking down and the hard starting but did not change the white smoke (especially thick on startup before the engine is warm)

I have found a couple more little air leaks by installing clear tubing both upstream and downstream from the lift pump (which the guy said he changed btw) I cleared all additional air bubbles entering into the engine post lift pump.

I have also installed a new return line kit for what it's worth.

I still have an engine that misses and does the jerking thing which is even worse coming off the interstate in 5th gear. The engine makes way more white diesel smelling smoke than it should probably from missing. You can hear it in the exhaust note.

I started cracking injectors earlier to try to see if there was some air bubbles somewhere causing injectors not to pop and when I cracked a couple of them the rough running engine didn't even change speed like it didn't even affect it.

So give it to me straight guys do I need new injectors?

Do I need a new injection pump?

Do I need to advance my IP timing?

Is air getting sucked in from somewhere I can't even fathom?

I put a mechanics stethascope on all the injectors and some of them do sound quite a bit different especially that one that didn't do anything when I cracked it.

What do you guys think? What should I do next I gotta get this guy up and running well before winter hits.

 

Get a quart of ATF or Diesel Kleen. Pull the fuel filter, dump it out (if you haven't already put a new one on), fill it with ATF/Kleen, put it back on, start the engine and idle for 15 seconds, then shut the truck off. Let it sit overnight or longer if you can then get it up to temp and run the **** out of it for a while.

If after this it still misses and runs rough, you can consider timing, new injectors and pump, etc.

 

Okay I am going to go outside and hit it hard with some ATF and let it sit over night. Thanks for your reply.

 

Get the injectors out and get them pop tested. The only way u know for sure how they are. However, I must say my idi ran quite well, I pulled the injectors and found out none of them is spraying right, all were dripping. I had a spare 4 sets of used injectors, 1 supposedly from a running engine and none of the 32 sprayed right. I have bought the injector tips and overhauled the injectors, shimed them to correct pop pressure, pop tested them and mounted them. It is running ok but still, I am not happy and want to try the new Stanadyne complete injectors and judge from there. Putting new injectors will put more strain on the IP, so doing that it will need retimed the IP, advancing it more compensating for the wear in the pump. These IP are really bad design and u might end up just replacing it as well. I wish Bosch made some kind of IP that could be used, problem with the IP solved forever.
The main problem with the stanadyne IP is the amount of fuel is first metered and then compressed. Thus no compensating for the wear in the pump. The Bosch pump first compresses the fuel and then meters the amount to be injected. As it wears out there is still room for compensating. The stanadyne basically runs only worse since the rew 1.

 

Check the water separator, it is mounted next to the Vacuum booster for the brakes, it will be full of debris as it has a screen inside. It is also prone to leaking air in as the relief valve on the bottom will be corroded from water sitting in. The debris most likely seals it now, so once u clean it be prepared for a leak. I just drilled the seat out and put a flanged tube in, jb welded it in place. Drop the tanks and clean them out, u would be surprised how much junk is in there. Doing so replace the pick up tubes in the tanks, most likely they are broken.

The reason I repair everything is I am located in Europe and there are no parts, everything has to be imported and the duty and shipping are killing me more than the prices of fuel.

 

Thanks for the reply Romel! Thanks for the extra little bit of info on the pump metering that is nice to know. Maybe we could compensate by turning up the fuel slowly as time goes on? What do you think?

Anyways, my truck has been sitting all night with Diesel Kleen sucked into the pump so I am heading out to see if that loosened anything up. Thanks again for your reply.

 

Turning the fuel up on the NA engine is useless, u only make it smoke and smoke means unburned fuel= wasted fuel. It is the simple equation, u can burn only as much fuel as much air is drawn put it in simple words. That is why u turn up the fuel when turboing, more air, u need more fueI. to make more power. The timing is crucial for performance and mpg. Save for a turbo, it is the best upgrade u can do, and to me intercool the air charge is the second best thing u can do. I would start with the compression test of the engine. It is easy, tells u the engine health regarding the combustion chambers. If compression good, move to pop test the injectors. Once u know u have good working injectors and still having issues the next step is inspecting the tanks, pick up tubes, lines and verifying the FSV is working right. Check the mechanical fuel pump, the rubber hose to it, it is prone to cracking, air intrusion.U want to rule out the cheapest things and move systematically to the most expensive parts. When having still issues I would suspect the injection pump, but only after u rule other things out. If u want to buy good used IP, Mike R. Green is the person to go to, he is on the facebook IDI diesel group. He can get u a good working pump for a reasonable money.
If u need help just ask, there are good guys around.

 

Romel, thanks for your replies again.

Okay so here is what happened today................the Diesel Kleen did absolutely nothing. I have included a picture that shows the truck idleing post Diesel Kleen. This is pretty much how much it always smokes.

 

There was a small bit of progress made today.....I got rid of the white smoke at idle not too long after taking this picture. I finally decided I would advance the IP pump about a dime and a half to the passenger side. I started the truck and the smoke at idle was instantly gone! I am still getting some intermittent white smoke mostly before warm when accelerating. I ended up worrying myself that I had advanced too far and backed it down about half of what I had originally advanced it so lets just call it 3/4 dimes worth of advance at this point and the idle smoke is still mostly gone.

I thought that the truck seemed quite a bit louder when the first advance was done and it was kind of scaring me like maybe I was going to hurt something because I don't know what can happen if you advance too much. I am going to dig into that right after I post this.

However with both degrees of advance I still have the bucking-jerking problem coming off the interstate while I let the truck engine brake in 5th gear and sometimes for a while after coming off the interstate at mild throttle in 5th gear around 50 MPH it wants to buck and jerk more than normal. What the hell is causing this? What is happening in that poor engine to make this thing do that?

 

I forgot to add that I did drop the rear tank and completely go through it and add a new fuel line bypassing the FSV for now to eliminate possible air leaks caused by the tanks or lines from the tanks. I also checked both upstream and downstream of the lift pump to ensure it was not introducing air to the system.

 

Today I bumped the IP back up a tiny bit and the truck definitely idles louder. It has more of the clatter now. When I accelerate I get little puffs of greyish-black smoke that clear up quickly but then again I am only at about 3/4 throttle I am not punching it and holding it. I think I am probably just a touch too advanced at this point.

Anyways when I get off the interstate in 5th now and engine brake on the ramp the jerking and bucking happens later down the ramp than it does when the timing is more retarded. Maybe slightly less severe too. I am starting to think that this has something to do with the injection pump somehow surging fuel to the injectors or something. Does anybody have any input?

Also driving around town I basically get no bucking and jerking where I used to get it in 4th sometimes so it has improved dramatically in that regard. Could have been coincidence too but time will tell more.

 

Generally stalling on decel indicates a sticky pump, I think metering valve specifically, but don't quote me on that. The fix for this typically is a diesel Kleen treatment like you have done. You may want to try giving it another dose for good measure and see if that helps, diesel Kleen is much cheaper than an IP.

​​​​​​​I suggest getting a facet duralift fuel pump, the 9-11.5 psi model is what I put on and it just supplies enough fuel. Your mechanical fuel pump may be crapping out and the pump is struggling to get enough. Since we don't know what exactly you mean by jerking, I'm going to assume surging and that in conjunction with it doing so at the end of an on-ramp (longer, sustained load) says fuel supply issue to me.

The other reason I suggest this is that it is a good investment no matter what. Some people debate semantics on staying "non-electronic" and keeping the mechanical pump for reliability. However I have only been impressed by improvements in starting, power, and reliability gained with electric fuel pumps.

 

Okay I am back. I have not given up yet, but just about pushed the truck in the river today out of frustration. I wanted to clarify the truck does better under load. When I am in 5th with my foot in the pedal on the on ramp it is okay. Not the smoothest but not bucking. It is when I get off the interstate in 5th (engine braking) that it starts to surge which causes the "bucking".

Anyways I had decided that it must be a fuel supply issue and my supposed new mechanical lift pump was not doing it's job properly. I went and picked up a fuel gauge and all the fittings to tap into my 1/2" pipe hole I made in the top of the filter housing (old fuel heater hole) so that I could watch the fuel pressure under varying conditions. This is what I noted. 4.5 pounds with a little bounce to it at idle bouncing lets say between 4.25 and 4.75 fairly rapidly (like pump pulsations). When I stepped into the throttle more I would get the pulsations to go away but it would just drop down to 4 pounds even and stay there. No matter how hard I got on it that lift pump is maintaining an apparent good pressure in that filter head.

One more curve ball. I went to my Ford guy at Autozone and had him look at everything when I still had my clear line downstream of the lift pump and when he revved the engine he could get a couple of air bubbles to appear from somewhere (possibly the barb to hard polyvinyl tubing interface that is about impossible to seal) and go into the filter housing. I am not sure where they were coming from but I never seen them in the clear lines when I was test driving and getting the "bucking" (surging when engine braking on the offramp) I never revved the **** out of it like he did either. Perhaps there is something mysterious going on in this lift pump after all I am not sure how to test it at this point. My new rubber fuel line leading to it is like double hose clamped and siliconed at all joints(except the final one at the bottom of the lift pump and that one is clamped tight!) (keep in mind I did drop the tank and check all of those problem areas at the shower head and all that....plus the tank is full and again the fsv is bypassed)

I did notice that the lift pump is wet I am not sure if that is from me bleeding fuel from above or not though. I did pick up a new lift pump because before testing the fuel pressure I was planning on replacing it but I am not quite so sure now. Seems like if it had a bad problem it would not maintain pressure so good. The wetness it worrisome though.

What do you guys think? I would really really appreciate some insight and any suggestions you guys might have.

 

First, when splicing the factory fuel lines they need to be heated so they sort of form around the barb, then no clamp is needed.

The only other way I've had lick splicing them is sliding 3/8's hose over it about six or so inches and double clamp it.

Second, your problem sounds like air, but since your truck doesn't completely stall I doubt it's the metering valve

If your able to get for sure all the air gone there is a stud on the back of your pump that should be torqx with a jam nut, loosen the nut and turn the stud in to decrease slack in the governor, it will also raise your idle. Adjust a little at a time (like 1/4 turn or so) and do it with the motor off, start, readjust idle if it's too high and try driving it. If it doesn't make a difference after a turn or two I would say it's not your problem. Which is why I think you need to check for air again before messing with the pump or replacing it.

The only time I've ever had any kind of bucking it was from a clogged fuel filter or air intrusion, you may need to change your fuel olives on your hard steel line. Ford can get them individually there pretty cheap, like a square shouldered o ring

We all have issues that are a pita, don't loose hope, an idis worst enemy is air,

 

Thank you Darkovercast for your reply. I did change out the 3/8 filter housing inlet olive and then the two 5/16 olives on the filter housing outlet to the IP. No change there. Earlier I stated that the advanced timing seemed to help but after I installed the fuel pressure gauge it was really driving like **** towards the end of the test drive. Surging more than ever so it is not timing related. It seems to get a lot worse after I work on it sometimes. (I know, I know after all I am trying to fix it)

Do I have to crack each injector line individually after I work on it or should the air clear from the injector lines once it is up and running? I feel like the air should bypass getting shot into the injector lines but perhaps small bubbles are making it in there and wrecking havoc.

Where should I confirm the presence of air? Should I go with clear line to the filter head inlet or rather clear line on that injection pump return line?

Thanks for the tip on the governor linkage I will try that after double checking for air like you suggest. I think your right though I think it's air too I just was having these problems back when I had clear line upstream and downstream from the lift pump and under normal driving conditions I would not get any air bubbles and the son of a bitch would still start bucking getting off the interstate. That means I saw no air going in but the effects of air coming back out! I am baffled! Maybe I should be looking at the return from the IP section though. My thinking is any air at all that has went through the system that did NOT go through the injectors has to leave that line if it were to affect the performance of the engine. Maybe my thinking is wrong.