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1999 Jeep wrangler: 4.0L V6 with approx 209k miles..50 mph..lose power…

1999 Jeep Wrangler 4.0L V6...
1999 Jeep Wrangler 4.0L V6 with approx 209k miles.

This is an intermittent problem which has developed recently but is becoming more frequent. Often, once I begin driving over 50 mph I suddenly lose power. It does not stall out, but the more gas I give it the more it slows down. If I pull over to the side of the road, the engine continues to run and normally once I drop below 35 mph everything returns to normal. I do not get a check engine light or any other type of indicator. It doesn't do this all the time, but there also does not seem to be a trend (it can happen 5 minutes after I start it up for the day or it may not happen for hours).

At lower speeds, it still runs like a champ (especially considering the mileage). This is my daily driver and I typically drive 75 - 100 miles per day.

Thanks in advance for any help you can give.
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Answered in 12 minutes by:
6/27/2010
Amedee
Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 28,316
Experience: ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Hello!

 

You could have a fuel delivery problem. I would recommend to start by checking fuel pressure. Fuel injected cars are very fuel pressure sensitive. Fuel pressure is very important and must be within specifications! But if the pressure is low, it does not mean the pump is bad. A plugged fuel filter, a pinched line, and low voltage at the pump can contribute to low fuel pressure. All three must be check before replacing the pump! You can get a fuel pressure gage at a local auto parts store for cheap.

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Customer reply replied 8 years ago
Thank you for your reply. I had the fuel pump replaced approximatley 1 year ago, and in fact ever since then my gas gauge has not worked properly. I have to rely upon tracking my mileage to know when I need to refueld. Since the pump and the sending unit are combined on this Wrangler, I have operated under the assumption that the sending unit got banged up during installation. Maybe this is related, maybe it isn't??

I am just concerned that I have a bigger problem, especially after the "no bus" message & dying out after I got a car wash yesterday.

If you think that the fuel pressure is an issue, then I will got to Oreilly's down the street and purchase a guage. Is there any trick to hooking one up?

Thanks again.
NO... it should just screw right to the fuel rail. THen you just turn the key on and start the engine right up and take a reading.
Amedee
Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 28,316
Experience: ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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THanks for the accept!

 

If you are getting a no bus message displayed on the instrument cluster, you might have a bad instrument cluster or a module might be shorting out on the BUS circuit.

 

WHen this happens, I would also recommend to check for reference voltages to both cam and crank sensors. SOmetimes these can short out pulling the bus system down.

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