I've recently developed a problem on my 1990 Ford E350 that I just bought. It only has 57,000 miles on it.

The engine starts and runs great, but with the slightest hills it bogs down and loses all power to the point to where I have it floored and it slowed to 25 MPH going up a hill.

I did a major tune up on it with Motorcraft parts. Cap, rotor, wires, and plugs. All new filters too. It just passed emissions with very clean readings, but no change on the loss of power issue.

I also replaced the high pressure fuel pump on the fram rail, but this was not the problem.

After I drove it around the block it had a hard time going up my driveway. I opened the hood and the exhaust manifolds and the exhaust pipe were glowing red hot. I can also hear detonation in the engine when accelerating.

I set the ignition timing to factory specs, which is 10 BTC. I checked it TWICE to make sure it was correct. Per factory spec, you have to remove the spout connector when setting the timing. I did do this as well.

I wonder if the cat is plugged. This vehicle has California emmisions.

 

It's pretty easy to check for a plugged exhaust, with a motor that size there should be enough of a blast coming out the tailpipe when it's floored quickly to knock a small child over. Also check fuel pressure at the fuel rail, it should build and maintain 40-45psi with vacuum removed from the regulator, if it's significantly lower than that you have a problem somewhere in the delivery system.

 

Sounds like low fuel pressure or clogged cat. Unhook the exhaust at the manifolds or replace cat with pipe temporarily and drive it. Power there, cats clogged. Power down, check fuel pressure. PULL THE CODES

 

Thanks for the info guys.

Could my DFR be causing this?

 

DFR?


Plugged exhaust, low fuel pressure, or bad MAP sensor could cause your issue.

 

DFR is the Dual Function Reservoir. A black plastic canister that's on the frame rail that the fuel lines from both tanks go in to.

 

I forgot the earlier dual tank trucks used that setup.

That would show up as a fuel pressure issue, either all the time or when you give it gas.

Fuel pressure should be about 39.5 PSI WOT, or engine off key on. Lower while idling. Fuel pressure should rise when you snap the throttle.

 

I have made some progress.

I replaced the catalytic converter and there is a significant increase in power. Replacing the converter was a good move.

However, I am still not in the clear yet. When cruising at 45 MPH for example, and I floor it, it does not increase much in speed. I still need to check the fuel pressure.

 

That was phased out in 1989.

 

This is a E350 van, which had it until 1991.

 

I'm real interested in this because I have the exact same issue with my 1990 E350 Chassis 7.5L gas motorhome. Runs great at low engine speeds but can't hit 55 unless I'm going down hill. Mine has the Dual Function Reservoir also, this MH sat for something like 10 years and only has 37,000 miles on it. I bought it last month and before I even tried to start the engine I replaced the plugs, wires, cap, rotor & fuel filter. I pulled the line off the DFR and ran the in tank fuel pump and only got about a cup of nasty fuel out. The fuel gauge was reading 1/4 tank so I figured the gas was gummed up or the sock was plugged. I dropped the tank and it was full of rust and junk. The fuel pump and sending unit was rusted and trashed. I had the tank cleaned and sealed and I replaced the complete fuel pump assembly. I turned on the key to run the pumps with the schrader valve removed from the fuel rail so all the old gas in the line could be purged. When the gas came out clean I started the engine and it ran great at idle and warmed up to temp. When I took it out for a road test it is acting just as you described. It really feels like fuel to me because if I ease the peddle down slow and I'm on flat road it will get to 55 but if I mash it in makes all kind of noise and starts to loose speed. The guy I bought the home from told be the last time he drove it it did the same thing to him. My first thought was the high pressure pump, then the fuel regulator, or MAP. I didn't suspect the converter because it has great exhaust pressure out the tail pipe. Please keep me posted.

If I unhook the fuel pressure regulator vacuum line will that ask the pump for full pressure at idle?

Thanks

 

Check your timing. Then get a fuel pressure gauge and check the pressure at idle and WOT. pull the codes on it

 

This issue is now 100% resolved and it now has the type of power that I expect from a 460 V8.

The problem was the Catalytic Converter was clogged. The other issue was that when I checked the timing the second time I forgot to plug the spout connector back in.

I also replaced the high pressure fuel pump and the Dual Function Reservoir which may have also contributed to the problem, but the largest increase in power was when the cat was replaced.

When I smash the gas pedal to the floor, that Econoline van is GONE!!!

I was in a big hurry to get this van fixed as I had to make a trip to Moab, Utah Friday night to pick up my new trailer I just bought and tow it home. It's a 16' enclosed trailer and I thought it was going to be slow going on the way back home with the trailer but the van didn't hardly feel it back there.

I would like to thank everyone that helped me with this problem in this thread.

 

Never mind, issue resolved.

 

I did that once... checked the timing and forgot to pull the spout back in. A lot of back firing and low power. Amazing how that lego piece affects performance.