Hello ya'll,
my 92 f250 7.5 won't start. I have checked spark(good) fuel pressure is 40 psi. I installed a new FPR and filter, map sensor, egr valve, pcv valve, ignition coil, new plugs and wires, new distributor and stator, and new timing chain and gears.
It turns over and tries to start but won't stay running. This started before I replaced all that I mentioned above. With all that new stuff it does the same thing still. Nothing has changed. At one point it did start and stay running but it ran really rough. Not sure what else to do. The motor has 207k miles on it. Is there any advice out there?

 

Hi Dusty,

There are some miles on that engine, so to determine where we stand, I suggest you do a compression test. You can rent a tester if you don't have one.

That test alone will tell us if the mechanical timing is good or not. Since it won't start, are the plugs wet or dry ?
Replacing a dist can create a whole new ball game if installed incorrectly..

Did you have the timing TDC mark in the crank pulley lined up with the pointer on the timing cover and make sure #1 cyl was on the compression stroke when you installed the replacement dist, with rotor pointing to #1 cyl on the dist cap ? If not, you will need to start all over again and do this or it will never run right ,,,if it starts.
If that mechanical timing is not done correctly even one tooth off, it will never run right AND this cannot be corrected adjusting with a timing light.

We take things one at a time, so how about a little history What was the original problem ?
The more things replaced,the more things can go wrong.

 

Before it wouldn't start, it ran a little rough like a cylinder was misfiring and that would come and go. My wife started it then moved it to run a plow where it was parked. She left it running while she cleared the snow but when she was walking to the plow truck she heard what she described as metal on metal pop. She can't say for sure if it was the truck or another noise in the area. It was windy that day. When she was done clearing snow she moved it to a different spot then shut it off. Later that afternoon she was going to move it back and that's when it wouldn't start up again.
when I replaced the distributor, I did point the rotor to #1 but didn't remember to look at the timing marks on the balancer. I guess I got lucky because it started when I put the new distributor in but was still running rough. The next day after I replaced the distributor I checked timing with a light then drive it around for about 15 min then parked it. It still ran rough and very under powered. The next day I started it to keep troubleshooting and noticed this time it was backfiring a little bit (but not bad) while it was warming up. I thought at that point the time chain was stretched out causing timing issues. Since I needed to put on a new timing cover anyway because of a water leak, it gets a new timing chain. I did all that making sure the marks were aligned and put on the new chain and gears the same way. Put it all back together and now it won't start. It tries to but won't.
I haven't done a compression test yet. With sub zero temps coming this weekend, I won't do that until it warms back up nectar week. I'm in Colorado and no garage.

 

Its bad enough when it is cold and damp, but the tools are cold, the engine parts are cold and its tough working with heavy gloves. NO FUN AT ALL !
Know where you are coming from.
If you are planning to start the recheck procedure,
You need to remove the spark plug for #1 cyl (pass side front) and you can tell when that piston is coming up on the compression stroke so you can line up the timing mark (TDC) on the crank pulley with the pointer on the timing chain cover. One way to make it easier is to bump the starter and feel for the pressure coming out of the spark plug hole.When you get close, you can use the alt pulley to move the crank pulley, in the normal direction of rotation. If you pass the timing mark you need to go around again normal direction of rotation no backing up. Don't forget there are 2 times that timing mark will come to the pointer. Only one time is on the compression stroke. The rest you know how to do.
Side note: sometimes you have to fiddle with the oil pump drive shaft to get the dist to go all the way down and be in the right place ,rotor pointing directly to #1 terminal inside the dist cap..

 

Just a quick update. I still haven't had the time to do a compression test on all 8 but I did brave the cold long enough to check cylinder# 1. Spark plug was dry. I used a screw in type compression tester, cranked it for 5 seconds and it showed 120 psi. Engine was extremely cold. I did this about a week and a half ago.
Today, I was going to do the other 7 cylinders but decided to check fuses then see if it would start. Fuses are good, It did start this time so, I put the timing light on it and set the timing to about 11-12 deg btdc. It does run a lot better now and the engine runs smoother but still sluggish. But while I was driving it around the property the check engine light came on. Code41. Just wanted to give you a quick update because I don't think this problem is solved yet. I'll be checking the compression on the other cylinders this weekend and I'll report back to you. Thanks for all your help.

 

The code 41 tells us the oxygen sensor is reading lean. It could be stuck lean due to a malfunctioning sensor or unmeasured air is getting into the cyls that is not being reported to the computer. Look for a vacuum leak, or a kinked/split pcv hose. Sometimes a hose comes off and is not easily spotted.
If the computer receives the information the mixture is lean,it will increase the injector on time ,,,up to a limit,,, which in this case has been reached and the computer cannot add any more fuel.

 

 

I did the compression test on all cylinders. When I was warning it up it was still running rough. I got it up normal running temp then took all the spark plugs out to do the test and all 8 cylinders tested at120 psi. I did follow the instructions you sent me. Thank you for that info. Number 8 cylinder smelt like gas, the others smelt like they were working fine. I attached a photo of the spark plugs. I put those in last summer and the truck has about 500 miles on it since then .
When I put the plugs back in and the wires back on it started right up, I was surprised it started that easily and was it running smooth so took that opportunity to check the timing again. It was off just little bit. I removed that gray plug by the test terminals and set the timing to about 12 deg BTDC. I took it for a test drive for about 25 miles and it ran smooth but still seems under powered and sluggish. That was a couple of days ago. Today, I started it but it took about 4-5 seconds of cranking to start. Code 41 is gone now and no check engine light. I feel like I'm chasing multiple issues


the order on the first Pic is left to right 8 -1.
2nd pic is top to bottom 8-1
I did check the gap before i put them back in.

 

The photo of the plugs removed shows a lot of black stuff which is not normal.

It looks like there is a lot of oil on them.If it is oil, we need to determine where it is coming from.. Restricted air intake could be one reason. That extra oil can plug the catalytic converter resulting in definite power loss.and also contaminate the oxygen sensor. Did you check the PCV system for possible restriction ?


That oxygen sensor will need to be replaced. You have a lot of work to do.When done let us know how it runs., thank you.