New fuel pump = bad gas mileage?
93 YJ 4.0L. My fuel pump went out the week after thanksgiving. I replaced it with a new pump and all seems good. Except for the fact that my gas mileage has droped big time. Before, I was getting 18-20MPG, now I cant get any better than 15-16. I dont get it? The fuel pump is the only thing that I changed (except filter) How can a new pump give me worse mileage? I havent noticed any change in power, no more or no less. Its not really cold down here yet, so I haveing been letting it idle in the AM to warm up. So its not that.
The old pump was the factory one, made by bosh. The new pump looked just a little diffrent and was made by carter. But no one had a bosh pump, only the carter.
'93 YJ 4.0L, AX-15, NP-231HD/SYE, 8.8in rear, OME 2.5 lift, WJ knuckle/brake conversion, hydroboost. Warn M10000 winch. Hope to some day build a stroker for it.
'79 Cherokee Chief, 401 MPFI fuel injection, T-18/D-20 and hydroboost. Otherwise stock.
Future mods: NV4500, NP205, high pinion D60 front and smooth bottom D60 rear, e-lockers front & rear. SOA with 35X12.50's