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Cardoctor71, ASE Master Technician
Category: Ford
Satisfied Customers: 675
Experience:  MasterCertified Technician with 35 years experience, Owner of two full service repair facilities
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What can cause gh negative fuel pressure on a E 450 ford

Customer Question

what can cause high negative fuel pressure on a E 450 ford super duty
Submitted: 2 years ago.
Category: Ford
Expert:  Cardoctor71 replied 2 years ago.

Please further explain high negative fuel pressure, so i can better assist you.

Customer: replied 2 years ago.
I got a check engine light on my 2005 Ford E450 motorhome with v10 engine, which turned out to be trouble code P0191. Fuel rail pressure sensor was replaced and light turned off. Engine runs fine but the light came back on. I noticed a small amount of negative pressure when unscrewing the gas cap. Replaced cap and then I noticed quite a bit of negative pressure with this cap when cap removed and engine is running. Light remains on and engine continues to operate normally. What can I do to keep solve this problem.
Expert:  Cardoctor71 replied 2 years ago.

Most likely you have an issue with the fuel vapor recovery system, particularly the evap/purge valve or charcoal canister.

Expert:  Cardoctor71 replied 2 years ago.

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