I have a 89 f250 that came with the 351w. The motor ate a piston last spring, so I pulled the motor to see if I could rebuild it cheaper than a junkyard motor.
Right after that, i got laid off, and couldnt afford either. So the truck sat all winter, and I managed to scrape together enough to buy a junkyard motor. I know the motor is good, I drove the truck it was in, had plenty of power, plugs were all nice and brown, had good oil pressure. I dropped the motor, in, hooked everything up, and hit the key.
The motor cranked over twice, and then bogged down, like it had a dead battery. I put in a fresh battery, and it still cranked over slow. I pulled the plugs and they are all wet, like the motor is flooding.
I cleaned them, put all except the #1 plug back in, put the wire on the #1 plug, and set it on the throttle cable bracket to ground it, and it sparked.
I had labeled all of the hoses and wires when i pulled the motor, and I dont have any leftover. I was wondering, which connections would be the most likely to cause this kind of problem. today I am going to pull all of the plugs and crank it over with no plugs in it. And then i will do a compression test.
My main question is, has anyone else had a problem like this with a new motor? If anyone has any ideas as to what could be causing my problem, I would love to hear it. I have done 3 or 4 motor swaps, but they were all 4 cylinder, honda or gm.

Had the same problem when I swapped in my 300. When I was done I had replaced the starter, battery, and all related cables. Turns over great now.
Oh yea, welcome to FTE!

different years had a different firing order on the 351.

I know the 302 changed firing orders but when did the 351?

Check all your cables at batt & starter.. Check all grounds...You can never have to many I have added grounds just to make sure..Lew

Sounds like it washed the oil off the cylinder walls.
Did you replace the distributor with your old one?
After you blow out the the cylinders with your air hose try holding the throttle wide open after it turns over once.
You may want to squirt a little oil into each cylinder to get it to turn over faster.
Also check and make sure that the throttle is closing all the way.

sounds like a weak starter. I second replacing the starter and cables.

I had the starter tested and it tested fine, the starter came with the motor, and it started the donor up fine. I took the starter back out after it wouldnt crank and cleaned all the connections, and took a wire brush to all the grounds. the alternator was also newer. I checked the compression today, and it tested at 110-120 lbs per cylinder. The book says that those numbers are low. Could that be because I tested cold? do the pressure numbers go up when the engine is hot?

It cranks over very easy with no plug in it (as it should) I am going to drop a little oil into the cylinders, and get some ether. I ran through some of my electrical plugs and a few of the have corrosion on them.
What could i use that would be small enough to fir in the plug to clean it? would spay on battery terminal cleaner work?

The distributor I used is the one that came on the motor, the motor is a 91 and my truck is a 89. Is there a difference? I gave away my old distributor to a friend who was having ignition trouble.

I didnt think the 351w had a firing order change. Am I wrong? I know the 5.0 changed and the 5.0 h.o. was the same as the 351w.

If you are talking about an electrical plug then you do not want to put anything in the holes that would spread them. I would say contact cleaner.

They should be the same with the Gray Ignition Module on the side. The module is gray and not black, right?
The firing orders are the same.

The module is grey. I am going to go get some ether right now, and a little bottle to squirt oil into the cylinders. And some spray on contact cleaner.

You may want to put some dielectric grease in those plugs also.

So I tried the ether, nothing, checked timing, and from what I can tell its on the spot. Has anyone ever had a starter test good, and still be junk? I have another starter, the one I took out of the truck originally, I am going to try that one. I cleaned out the plug to the ignition module, and put dielectric grease on it, that is a given when I work with electrical on anything automotive. I cleaned the plugs on the trottle body, I cleaned the plugs to the sensors on the intake. There has to be something I am missing. I am going to install the old starter now, but I dont know what kind of difference that will make.

i read a thread the other day about starter testing being a bunch of b/s... someone said that all they do is spin it and measure resistance or something in a little box with no load applied, apparently its a lot different when actually installed and under a load. I can't remember what thread it was or I would point you in that direction, but basically the way they test them is not consistent with how they actually operate

I put my old starter on the truck last night, it works much better. the new one is a remanufactured unit from somewhere. the motor spins right now, but it still will not fire.
I am having a hard time checking the timing, because the engine isnt running. Is there a way to check it without the engine running? the timing light lights up the general area, but I cant get a good look at it.
This thing is starting to irritate me, everything that it needs to run is there, it just wont run. I really need this truck running, I have a load of yard work to do, and the s-10 just isnt big enough.

Just turn the crank to tdc on the pointer on the compresion stroke then pull the cap & see if the rotor is pointing at # 1 wire or close