7.4 ltr Engine Trouble - Help!

[ebg338]

Well the family and I are in a bit of a pickle. We're on our way to Orlando in our 1992 Winnibago Adventurer. Has the 7.4 ltr Chevy with ~48,000 miles. Serviced it last year with plugs, wires, distributor, tranny fluid, coolant, air filter. Ran perfectly until recently. I noticed every now and again it would hesitate/stumble at low RPM and then run fine again.

This afternoon it became significantly worse. At low RPM (traveling at ~60 mph) it began to stumble/bog badly and then suddenly run okay again. A few miles later, same thing. We pulled off at Cave City in KY. Pulling into the campground it was running poorly - no power, then would suddenly rev up and be okay. I checked all the connections on the engine for anything loose/obvious (plug wires, any wiring on the motor, etc.) I'm thinking possibly the fuel filter or fuel pump? Anyone experience something similar? Opinions / suggestions would be greatly appreciated.

Thanks much,
Bill

[Sammie]

I had a 1990 Pace Arrow with the same engine. Try the replacing the fuel filter first, you might just get lucky. To change the fuel pump, the fuel tank will need to be dropped.
Did this problem just start after filling up the tank with new fuel. If so you could have got a tank of bad gas with water in it.

Sammie

[justimagination]

Quote:

Originally Posted by ebg338 Well the family and I are in a bit of a pickle. We're on our way to Orlando in our 1992 Winnibago Adventurer. Has the 7.4 ltr Chevy with ~48,000 miles. Serviced it last year with plugs, wires, distributor, tranny fluid, coolant, air filter. Ran perfectly until recently. I noticed every now and again it would hesitate/stumble at low RPM and then run fine again. This afternoon it became significantly worse. At low RPM (traveling at ~60 mph) it began to stumble/bog badly and then suddenly run okay again. A few miles later, same thing. We pulled off at Cave City in KY. Pulling into the campground it was running poorly - no power, then would suddenly rev up and be okay. I checked all the connections on the engine for anything loose/obvious (plug wires, any wiring on the motor, etc.) I'm thinking possibly the fuel filter or fuel pump? Anyone experience something similar? Opinions / suggestions would be greatly appreciated. Thanks much, Bill

................. Ran perfectly until recently. I noticed every now and again it would hesitate/stumble at low RPM and then run fine again.

My guess you have just filled up the tank, right, I think you have gotten some bad fuel. You would think with the price of gas today that cannot happen, but it does. Water in fuel tanks is not uncommon this time of year. Go to Wal-Mart in the auto section and get a bottle of Sta-Bil fuel stabalizer and dump it in the tank. Someone else on here may have other products they have used. Good luck, travel safe.
David G.

[Midniteoyl]

Agree with sammie... try the filter, but betting its the pump. Classic symptoms.

[ebg338]

Thanks both of you for the responses. As a matter of fact, I just put almost 50 gallons of gas in the tank today.

I'll see about getting some stabil into it tomorrow morning. Do you think this will be able to take care of the water (if that turns out to be the issue) or would something else work better?

Any other thoughts are very appreciated.

Thanks,
Bill

[Sammie]

If you just fueled up today then water in the fuel sounds like your problem. Any good auto parts store will carry fuel stabilizer. Lucas makes a very good product. I would buy enough to treat a full tank of gas and I would still change the fuel filter after running the engine for a while.

Sammie

[LVJ58]

If yours had the Throttle Body Injection (TBI) system you could have a bad Throttle position sensor or injectors. Check all the connections first. Also check for any leaking or loose vacuum lines.

Good luck and keep us posted

[JohnRR]

Heet in the red bottle is what you want to try (commonly called gas line antifreeze) the red bottle contains isopropal as compared to the yellow bottle which contains alcohol. It's sunstatially cheaper than stabilizer or cleaners as all it does is chemically make the drops of water smaller so they can pass through very small orifice opening in the carburetor.

Stabilizers and cleaners only contain a very small percentage of what you need to alter the properties of water.

One bottle for every 10 gallons of fuel or in your case not the 50 gallons you just put in but the capacity of your tank and an extra bottle or two would not hurt anything either.

[Midniteoyl]

Iso-Heet (red) is isopropanol as stated..

Heet (yellow) is methanol

[ebg338]

Good news to report. Kept fiddling with the RV this morning and finally got it running well enough to get to Autozone. Picked up a new fuel filter and 8 bottles of heet. Changed the filter, added the heat and filled the tank to the top (Shell premium gasoline - don't know if the higher octane mattered but figured it couldn't hurt). Started it and after a few minutes it ran like a top. We managed to make it south of Atlanta today. Vacation's back on!

BTW - Autozone had a fuel pump so I bought it, figured it couldn't hurt to have a backup.

Thanks to everyone for your help!

Bill, Erin, Sam, Matt, Josh

[Midniteoyl]

Quote:

Originally Posted by ebg338 Good news to report. Kept fiddling with the RV this morning and finally got it running well enough to get to Autozone. Picked up a new fuel filter and 8 bottles of heet. Changed the filter, added the heat and filled the tank to the top (Shell premium gasoline - don't know if the higher octane mattered but figured it couldn't hurt). Started it and after a few minutes it ran like a top. We managed to make it south of Atlanta today. Vacation's back on! BTW - Autozone had a fuel pump so I bought it, figured it couldn't hurt to have a backup. Thanks to everyone for your help! Bill, Erin, Sam, Matt, Josh

Good deal... and good buy on the pump for the 'just in case'. Did you pick up another filter too? You might as well change it again in 2-3 tanks if there is indeed water in the system.

[ebg338]

Didn't think of it today but definitely will. Best 11 bucks I've spent. Thanks again.

[JohnRR]

Thank you for the up date.

[Mekanic]

Glad to hear on you are on the road agin. Vehicles that sit a while do need attention to fuel tanks (water removel) and also once one is 10 years old hydralic brakes can use a good flushing out.