hertfordnc

Just picked up a great 91 XLT with only 66,000 miles and a strange problem.

Truck starts and runs great but it will not restart if shut off after it gets warm.

It turns slow, like the starter is dragging. The fix is to add more amps, like a jump box or a second battery. Previous owner carried an extra battery with him.

He and I have owned over 100 cars between us and we're old. You can assume all the obvious stuff has been ruled out.

New starter, new cables, assorted tune up parts. He also took it to a good local garage. They couldn't figure it out either.

He pretty much gave me the truck because he didn't want to mess with it any more.

Thanks

I hope someone here has some insight.

Dave

Manuellabour247

Check your grounds going from the engine to body, frame to body, and frame to engine. Does it have a starter relay on the passenger side of the truck between the starter and battery?

hertfordnc

Yup, 80% of all electrical problems, particularly starting problems, on old vehicles are caused by bad grounds. Cables were replaced by local shop. Yes, it has the relay on the passenger side.

My hunch is that one of these things that was supoosedly already looked at needs to be revisited.

thanks

Dave

Manuellabour247

If they didn't clean the contact areas really well and apply some type of dielectric grease to prevent rust, it may need to be cleaned up with a wire brush. No sense in throwing more money at it if it's something simple.

Also check the vacuum lines for any obvious cracks or signs of old age. There's a couple ways to test them and the diagrams are on here somewhere. Obviously it's getting air, fuel and spark. Have you verified the correct timing?

What cold cranking amp battery are you running?

fltdriver

It could be something as obvious as alternator. What you need is a multimeter and test current flow at startup. But my guess would be something along the lines of a failing ignition coil, pip sensor, or ect sensor. All 3 a notorious for "killing" engines but will also prevent starts after truck is at temp.

hertfordnc

The mystery continues.

It's really cold here and I don't have a shop so I'm just trying small things to understand the problem and hoping an answer will emerge.

All the obvious stuff has been discussed with lots of very smart people.

I took a battery out of my cummins truck. this battery would crank a 17:1 diesel at 18 degrees F. but it would struggle to start this F150. Then i jump it with another vehicle and it starts right up.

In the years that the PO has been messing with this he changed EVERYTHING, starter, alt, cable, solenoid, etc. In that time he only put a few miles on the truck.

Thinking the alt might be weak, I put a charger on the battery, no change.

I don't mean to sound cocky, I've owned a lot of cars and I am surrounded by old Ford loving rednecks, I don't post questions in forums until i've done a fir bit of research.

This is a real mystery.

My hunch at this point is that one of the repairs that has already been tried was bad, like a bad alternator from the reman (it happens often enough)

But it seems like no matter what battery is in the truck, it needs just a few more amps from another source to start.

thanks

Dave

hertfordnc

The mystery continues some more....

The wifes truck is a 2004 Explorer with BRAND NEW battery. Starts instantly with no drama.

So i connect the cables to the explorer with the explorer NOT RUNNING, just the extra battery, fully charged (with a charger)

So we have two good batteries, connected by jumper cables and the F150 cranks slowly and does not start.

Then i start the Explorer, -- so that adds about 1.5 volts and up to another 130 amps and the F150 starts instantly.

I've jumped lot of cars under a lot of different conditions and this seems like strange behavior.

I know, at some point I need to crawl under the truck and refresh all the connections but the ground is COLD.

THanks

Dave

fltdriver

Grab your multimeter and check for voltage at the starter.

It truly sounds like the current is not being carried for whatever reason, maybe internally damaged wire, wrong part put on by PO. When you are starting the truck you do have everything turned off (radio, lights, blower fan, etc...) correct? If not it maybe one of those pulling extra amps at start and not letting enough juice to the starter.

broncojunkie

When you jump the truck and it turns over like it should, maybe it's not because of the extra power, but because the ground is good. Your jumper cables not only carry power over to your starting system, but also provides a healthy ground.

This was my first guess, however, you also stated that the previous owner carried an extra battery. Assuming he just used jumper cables from the extra battery and it started, then I wouldn't think he would have been affecting the ground in any way. A bad ground can keep the battery from charging correctly, I guess. But to check the grounding system in your truck, you can use jumper cables. Just hook one end to the negative terminal and the other end to the body or frame. See if that helps.

If you can't find an issue with the grounding system (and yes, I would still suggest double checking all of your grounds, starting with the battery) then I would double check that starter. Have you taken it off and had it re-tested? Maybe even hold a heat gun to it to get it hot while bench testing it. If everything checks out ok, then I think I would try a high-torque starter...something with a little more power. I do know that the factory charging systems on these trucks are nothing to brag about, but a good battery should help turn that thing if you choose to go that route.

Just a couple suggestions.

djfllmn

iTrader: (1)

yea check grounds..also when you are cranking the truck do the battery terminals get warm?