Hello! I've got a 1986 F250 6.9 that is just generally a hard bitch to start. I call it the 4 crank method. I've got to cycle the glow plugs a couple of times, crank it over. Crank it again. Crank it a 3rd time. Then on the 4th-5th, it'll generally start. If I let it sit for 10 minutes after an hour drive. Same deal. Hard start.

I've had the batteries load tested, and they are tested as good.

This truck, runs awesome, but under load occasionally (depending on throttle position), blows blue smoke. At idle, it smokes a lot. Under power, it doesn't. I can drive at 60mph, and the truck runs GREAT. Let off the throttle a bit to slow down, and watch the blue smoke puke out the exhaust. Sometimes, it feels like the accelerator is stuck slightly open, as I don't slow down as quickly as expected when I'm off the throttle.

I don't want to influence the helpful suggestions, but my mind tells me this is possibly injector stiction. Which one, or how many, I have no idea!

This truck has at what I believe is 164k miles, but it could possibly be 264k. It's impossible for me to know for sure, but I highly believe it's 164k miles.

My father owned this truck for 15 years, and in the last 5, it's only driven 5k miles. I've driven it more in the past 6 months than he did in any single year in the past 10.

I recently flushed the coolant, replaced a faulty vacuum pump, replaced a heater core and it's running clean fuel.

I would really like to fix this hard start bull****.

I'm going to do a full oil change, along with fuel filter change, and then I want to resolve this hard start.

What's the first step? New glow-plugs, as we have no idea how old these *******s are?

New injector o-rings, fuel lines, clamps, washers, etc?

Thanks for your help everyone!

 

Check the glow plugs first and replace any failed ones.

A good rule of thumb is new injectors every 100K miles or 10 years in these mechanically injected diesels. The pop pressures end up allover the place after about 10 years. Do not even mess with rebuilt injectors brand new stanadyne ones are the same cost and can even be cheaper then rebuilt ones. Buy only Stanadyne injectors.

At 164K miles it is a pretty good bet the Injection pump is also worn and out of spec.

Get the glow plugs checked and make sure they are all getting power during the glow plug cycle sorted and if you are still having hard start issues give us a shout back.

 

This is great info. I'll definitely tackle this tomorrow. Glow plugs first. Then possibly injector o-rings. Then new injectors.

Hopefully it's not an injection pump.

Thanks for this help!

 

Each glowplug should read very low ohms to the engine block, almost a short. That means it's good. Some people take a testlight and clip the one end to the battery +, and then after unplugging all the glowplugs, touch each one and if the glowplug lights, that means the glowplug is good.

If you have the early type glowplug controller that screws into the back of the engine, that controller has a high failure rate, and is known to stick on and burn out the plugs. Most people change it out, get rid of it and go to a manual button, or go to the newer 7.3 glowplug controller.

P.S. I went back up and looked and you have a later model 6.9. There is a chance you already have the later controller. It is mounted behind the aircleaner and looks like this.

 

P.S. I do not know about the 6.9's, but the 7.3's have problems sometimes with valve guide wear. Do you have a "chuffing" noise out of the tailpipe? That could be a sign your valve guides are worn, and that can be where the blue smoke is coming from. They get really bad and it's usually easy to spot, just pull the valve cover and see if you can wiggle the valve spring/top of the valves back and forth.

 

Do you mean if the testlight illuminates?

One caution when testing the glowplugs. The emissions diagnosis manual says these glow plugs are actually 6v models, indended to heat very quickly on 12v. To prevent burning them out, the controller cycles power on and off. The manuals warns they will quickly burn out if operated continuously on 12v. So be careful not to damage them while testing. A test light should act as a current limiter, and should be safe to use as suggested, but I'd still make it quick to be on the safe side.

If testing with an ohmmeter, watch out because very misleading results are possible. A heating element at rest will have a very low resistance, looking almost like a dead short as previously mentioned. The resistance of a good heating element spikes way up under load, thus limiting the current to a reasonable level. However, a bad heating element can have an internal short to ground that looks within specs when tested cold. Under load, though, it no longer behaves properly, typically drawing too much current. Under some circumstances, a bad glowplug can excessively draw down available voltage but not blow a fuse. This unexpected low voltage causes all the others to run cold and is easy to miss unless deliberately checking for it.

On other diesels, I've tested the glow plugs individually with an ammeter. With a constant input voltage, I could see each glow plug was drawing amperage within a certain range, which told me they were good. Too much amperage meant a partially shorted heating element. Too little amperage meant a weak spot in the element.

I had amperage specs for those engines, but I didn't see anything in the Ford manuals. You could safely experiment with the Ford glowplugs and extrapolate some values for comparison, just be careful to use a 6v power supply, not the 12v battery. Kind of a moot point for most, as few people have a 6v source, but if you do, comparing individual amp draws is a very conclusive test.

 

Yes, thank you.

And on the tests, I supposed you could get some intermittent or shorted plugs, but in the real world I have never seen it. If they are shorted they usually go ahead and burn out. And I would never put voltage on a glowplug to test it unless I was bench testing it, for what reason I don't know. The ohmmeter or the testlight usually is good enough for a "go no go" quick test.

You can rewire these systems to a manual pushbutton switch. It works very well, but some people still frown on using it. And then some people say they have inexperienced people driving their trucks and want to keep the automatic system. There are many pieces of equipment out there that came with a manual system from the factory(like tractors, skid steers, backhoes, etc.) I have converted mine to a manual button, and I would never go back to the automatic system I had, it's too problematic. As long as you don't hold the button for more than 10 seconds, it will never burn out the plugs, even though they are 6v.

 

Thanks for this info, I really appreciate it!

I learned today from my dad (previous owner for 15 years) that the following maintenance was done:

REPAIRS
141,500 MILES 9-8-03

8 port side injector o-rings replaced
3 port side glow plugs 9-10-03
1 controller (glow-plug)by Dave-Precision 9-10-03 $132.40

The truck now has 20k miles more, over 14 years...

Tomorrow I'll fire it up and check that the glow plug relay makes a slow "tic tic tic" sound.

Maybe post a video of the exhaust and what it looks like when running.

I'll pull the glow plugs, and test them all.

Is there a way to determine if I should replace the o-rings on the injectors? Or to test an injector/s?

Thanks everyone!

 

No way to really test the injectors insitu they need to be pulled and checked on a injector tester for spray pattern and pop pressures. At that age and mileage it is probably just best to replace them. Also as the injectors age they pop pressures fall and this advances the timing.

And if you are pulling the injectors your are doing the o-rings. And if you are gong that far might well spend the $60 for new return fittings lines and o-rings. Be warned though sometimes new injectors can take out a marginal injection pump.

 

The O-rings only need to be replaced if they leak air. If they are leaking fuel, than they are probably leaking air also.

 

Well, in my ignorance, I didn't realize that the starter motor was on it's way to giving up the ghost. I didn't know the difference between cranking over slowly vs. cranking over like it's supposed to.

2 weeks ago, it was particularly hard to start, and I blamed the 5 year old batteries. I replaced them both, and guess what? Nothing changed. Except I have brand new batteries now.

This past Sunday, I drove the truck to my local Home Depot to get some insulation, and low and behold, it wouldn't start for the drive home. And, to top it off, the starter seized during my failed attempts to start it. I had to have it towed home. Luckily, it was only a 6 mile tow, for $100...

I ordered a new starter motor the same night, $106 to my door, and installed it yesterday.

The truck now starts so fast, so instantly, that it's almost unbelievable.

It starts like a 1.6L 4 cylinder gasoline Honda Civic with 5 miles on it. It's ridiculous.

I appreciate all the help that is available on this forum! Still going to install new glow plugs sooner than later.

 

Good to hear you found the issue and thank you for posting what you found as it may help others.
Dave ----