Fredbird

My friend told me that he's seen this sort of behavior before where the Fuel pressure will look okay at just "System On" but when it tries to keep up with the demands of the engine Under load, it will not not be able to keep up and you end up with lower fuel pressure than required.

I am going to look into replacing the Fuel Pump to see what that does. I have a $50 discount to use at Adv. Auto Parts, and since the Bosch Fuel pump only costs $87 it's like I got it for $37 bucks. Not bad, and from what I've read, the fuel pump is not difficult to replace on my car. Got any tips on that? Might do it over the weekend.

Jamesnns

I'm late to this party.

I bought injectors from FIC about last Jan 2011 ? Give or take.
My 91 runs just fine. I have no noticeable difference in fuel mileage.

Alan777

Jon is sending me new bosch injectors. I asked about the fuel mileage issue and he said it was resolved. They should be in the car but early next week, and I'll report back then.

(my car is currently not running due to 6 bad injectors)

GREGGPENN

I don't remember if it's mentioned in this thread yet, but many C4's have an issue with FP when the tank is only 1/4-1/3rd full. Most often (when this issue is reported) people talk about cutouts in hard turns or at the track. Track problems are normally for built cars.

Mine has that problem. If much below 1/3rd of a tank, it will cutout during a hard WOT pull. I'll usually get to around 4k rpms and cough, cough, cough.

Measured it with scans. Filled it with gas and the problem goes away. Needless to say, I keep the tank on the top half now.

Fredbird

Bought the new Bosch fuel pump. Will try installing this weekend.

I will report the results.

Fredbird

I "JUST" finished installing the new Bosch fuel pump from Adv. Auto Parts.
(Side Note: I liked their pump/kit because i was able to clip the new wiring harnes to the end of my old one and then to the pump. No wire cutting/disconnecting/splicing)

Performance seems to be improved under load. So I may have been starving the engine for gas upon hard accelleration.

Once or twice it did seem to hesitate when I hit the gas hard, but it was kinda' cold outside... apx. 40F

As to the gas mileage, I was able to watch the "on dash" calculator and it looks to have improved by a few mpg. while driving on the highway it is hovering right about 20mpg.

Recap: At this point, Fuel Pump Pump, Strainer, In-Line Filter, Fuel Pressure Regulator Diaphram, Fuel Raill O-Rings, and injectors have all been changed in the fuel path.

I will fill it up this week, and drive it for a while to get my "Hand Calculated" average gas mileage.

After that I will report the results.

GREGGPENN

If you haven't done so already, disconnect the battery for at least 1 minute. That resets trims and gets you to the new MPG as soon as possible.

Best way to measure...
1) reset ECM (battery)
2) drive for at least 1 day (to get ECM "re-adjusted")
3) fill up
4) drive
5) fill up and calculate

Fredbird

I have done #1 and am in the process of #2. I will fill up again and calculate on Monday. (my drive to work is all highway with no traffic. It should be a good measure of highway mpg.)

GREGGPENN

I (and we) appreciate your being anxious. Unless you have an extremely long drive to work, it's nearly impossible to get a good reading on less than a tank or two of gas. That's because it's hard to top of the tank exactly the same each time.

Make the test meaningful.