4.9L Inline 6 bogs down when fuel is added , won't start

Hi guys.

I have a weird problem with my 4.9L engine on 1988 F-250 with EFI system.
At first it seemed to be the fuel pump relay, but when I connect a FP gauge to the schrader valve and hot wire the relay, the pump comes on fine and there is lots of FP. I've verified spark to all cylinders. Here's the weird thing, when I don't hot wire the relay and no FP, the engine cranks over normal. But when I add fuel, it bogs down and acts like there very high compression in the cylinders.

I've check for an open injector with the spark plugs out with FP there were no flooded cylinders (hydraulic lock), but it doesn't make since that as soon as you add fuel it bogs down and while still cranking if you shut off fuel it gradually over a few seconds stops bogging down and cranks normally. It sounds like a stuck injector dumping fuel but looking at each cylinder, none are filling up with fuel. I've tried taking out one spark plug at a time to isolate each cylinder, but it does the same thing. Although it didn't bog down when all spark plugs were removed and fuel was added while cranking.

Any ideas? :eek:

So you actually have a slow cranking problem right ? Load test the battery,check the terminals, starter,etc,etc.
Phillip

The battery was charged. I finally figured it out. My friend had her friend work on it and they had messed with the spark plug wires at the distributor. Upon re-assembly, they based the #1 wire off the marking on the distributor cap. Everything looked correct because the cap was marked with number one and the firing order was correct. But when I went to verify the wires based on number one at TDC, the rotor was pointing to a different wire. Since the cap is idiot proof, I can't see this happening unless the cap was not right for the vehicle or someone originally rigged the distributor wrong. However, when I re-arranged the wires based on #1 cylinder, it started right up. Number one was not number one that was molded by motorcraft into the distributor cap. Regardless, the bog down was due to incorrect timing. Interesting.