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Edward
Edward, ASE Certified Technician
Category: Ford
Satisfied Customers: 2768
Experience:  ASE certified. Auto Transmission rebuilder for Ford Motor Co. from 91 to 2000
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I own a 93 Ford E150 conversion by Winnebago w/ a (302/5.0)

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I own a '93 Ford E150 conversion by Winnebago w/ a (302/5.0) V8 engine, automatic trans. that's been well maintained. Recently I noticed it was running a bit rough and acceleration/performance from stop and through the lower gears was noticeably bad...I thought maybe I'd gotten some bad gas so I added premium to see if it would help...it didn't. Any ideas? (no trouble light flashing)
Hello and thanks for your question. My name is XXXXX XXXXX I will do all I can to help.

Let me first ask, have you gotten the engine tuned at all recently? Such as spark plugs? wires? cap ? rotor? fuel filter? Are the normal maintenance items up to date? Let me know. Thank you.
Customer: replied 3 years ago.

I recently changed the plugs, thought about doing more but it was running fine....this came on quite suddenly

Alright, If the normal maintenance items are up to date (fuel filter air filter plugs etc.) It sounds like a constant misfire to me. I would first recommend a new cap rotor and plug wires. I know they are not fun to get to on a Van, but , if the wires are old, they could be arcing out the side of them before spark gets to the plug.

If you can raise the hood and pull the dog house out, you can spray some water on the wires and see if you see them arcing out the side anywhere. You can also hear them and it will sound like an audible zap if spark comes directly out of the wire. Look near the distributor cap and wet the distributor cap and see if you see sparks.

If all that looks good, I would get a fuel pressure gauge and check fuel pressure with key on engine off, and with engine running.. should have between 35-40 psi. and move up slightly when you give it gas, if it doesn't move up slightly when you give it gas check the fuel pressure regulator and pull the vacuum line and crank up the van, make sure no fuel is leaking out the vacuum port. I believe you'll find your problem in those items.
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Customer: replied 3 years ago.

Ed, I understand everything you told me except checking the fuel pressure with the "key on engine off", and engine running

A fuel pressure test is done with a mechanical fuel pressure gauge. You hook the gauge up to a schrader valve on the fuel rail. This will look similar to a valve you put air in on a tire. unscrew the cap and the gauge will install on the fuel rail near the injectors.

The specification for your van is 35-45 psi , 35 running at idle is ok. and pressure should shoot up to 40-45 psi when you give it gas.

The Key ON engine OFF test, is done by hooking the gauge up, and just turning the key to the ON position, do not start the engine. The fuel pump is suppose to cycle for 2-3 seconds to build fuel pressure. After it builds fuel pressure, pressure should hold in the fuel rail for 10 minutes. if it drains off quickly. that is a sign an injector could be stuck open. It should hold pressure steady after you shut the key off.

Customer: replied 3 years ago.

OK Ed, I'll get right to it, and thanks for all the help...should I let you know how it works out? It's the first time I've used this service, so let me know if I should follow up. Brad

Absolutely, thank you. check those things out first and I beleive you'll find your problem there. and you can follow up with me anytime. This question thread stays open for 30 days I believe.
Customer: replied 3 years ago.

Ed, You mentioned changing the fuel filter and this van has a pressurized fuel system, can you tell me how to safely depressurize it?

Yes, what you want to do, is locate the schrader valve on the fuel rail, and take a small phillips screwdriver, small enough to fit down into the valve, wrap a rag around the screwdriver and around the top of the fuel rail near the valve, and push the schrader valve open with the screwdriver. This will bleed off access pressure, There won't be much gas that comes out. maybe 1/2 an ounce at the most.
Customer: replied 3 years ago.

OK, great...sounds easy enough...thanks again, this is a great service!!

Yes, that job isn't difficult. Let me know if you have any further questions and please rate my service positive. It does not close the question. You can come back and follow up with me at anytime. Thank you Brad.