Smoking

Mike327

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1994 F350 7.3 idi turbo ZF5 swap

Recently truck had been getting hard to start when cold and excessive cloud of smoke when it eventually started. Then it would idle and smoke. When driving down the road no smoke in mirror. When I let off the throttle it will smoke again. Not burning any oil from what I have seen on the dipstick.

I noticed several of the caps on the return lines were wet with fuel. I replaced all caps, o rings and hoses as well as glow plug controller and glow plugs since the original controller was melted (probably due to 2 broken glow plugs which were laying on the and shorted and melted the glow plug wiring harness) now there is no visible fuel leaking or seeping out.

Now after replacing the above when starting the wait to start light comes on shortly and goes out. Crank engine for a long time and it puffs smoke entire time while cranking. Eventually it will start and blow excessive smoke and then same thing. Smoke while at idle and smoke when letting off throttle. Truck has 192,000 miles. Unknown if pump, injectors are original or not. Would a bad injector cause this? Not sure where to start. I don’t have a way to check the timing unless I buy the tools needed. Nobody local to me in Plant City, FL has them that I know of to help.

Just kind of lost on what to try next to diagnose.
 

franklin2

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The starting problem is common. Your controller is short cycling because there is a problem in the glowplug circuit, either a bad glowplug or a bad wiring connector or connection.

I know you just put in new glowplugs, but I would double check them for being good. Unplug ALL the glowplug connectors, and then with a testlight clip the testlight ground lead to the + on one of the batteries, and then touch the probe of the testlight to the wiring tip of each plug. The testlight should light if they are good.

If the glowplugs are good, look at the wiring to the glowplugs. There should be no corrosion and the connectors should fit tight. Usually the plastic on the connector rots off, and then you lose tension on the connector. This can be a problem.

The glowplug controller monitors the glowplug current as it's glowing the plugs. As the plugs warm up, the current drops to a point that the controller stops glowing. If you have a bad glowplug or poor connections to the glowplugs, this will lower the current through the controller and it will short cycle, making the engine hard to start.
 

franklin2

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P.S. Another common problem I forgot to mention is the wiring plug near the pass side valve cover. There is a bundle of wires that leads from the pass inner fender to the top of the engine. Near the A/C box there is a large wiring plug. Check to see if it's melted.
 

IDIBRONCO

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I think that you have two problems here. The first would be in the glow plug system. Franklin2 covered that pretty well. I think that your second problem is that you have retarded timing. Even without access to timing tools, you can do some experimenting. With the engine not running, you can rotate the top of the injector pump toward the passenger's side. Using the lines on the pump and the housing, move the line on the pump about the width of a dime. Tighten the three mounting nuts on the pump and see how the engine runs. Using trial and error, you can get your timing fairly close using this method. If you eventually come to the conclusion that you need to buy new fuel parts, the pump and injectors should to be replaced as a set. Their internal parts all wear at the same rate.
 

Big Bart

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Your glow plug wait to start light should go on for 9-15 seconds when the engine is cold. If it only goes on for 1-2 seconds it is because like Franklin mention the resistance of the system is off, the controller sensed it and shut off the glow plugs. The controller will cycle on, off, on, off, but the GP’s will not warm up. So you probably have some damaged glow plug connectors or damaged to the wiring harness. With a good system when 3 or 4 glow plugs die the controller only runs the glow plugs for 1-2 seconds and shuts off.

So make sure your connections on the controller are good and you wired it all correctly. (Otherwise you are likely to replace parts to later find out you mis-wired something.) Now test with a volt meter that you have +12v to each glow plug connector when the controller is on. Unplug all the glow plugs. Make sure the big terminal with the large yellow wires has +12v going to it.(Power from the batteries.) You can add -12v (Ground) to the small glow plug controller terminal that has the small white wire going to it. That will engage the solenoid and send power to the left a right side glow plug harnesses. Now you can test each glow plug connector for power.

If the wiring harness has power at each connector you will need to retest each glow plug for continuity. If the glow plugs are all good then likely your GP wiring harnesses are bad. You can get replacements from classic diesel design. You should never assume new parts are good, but is more likely your harness has been damaged by shorting out than your néw glow plugs and controller are bad. But don’t assume that. So you can try to repair your old wiring harnesses but at ~30 years, it would be good to replace them.

Also does your -
1) Cold idle solenoid engage after you push the gas pedal down half way and release when the engine is cold. It should raise your idle by 100-150rpm.
2) IP advance solenoid work. This makes your truck clatter loudly upon start up when the engine is cold. But it will quiet down about 60-180 seconds later.
 

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