I have a 1989 vett with 64000 miles on it. The car was dying out when it gets hot and missed real bad. I put new plugs, wires, distributer, rotor and cap, and new fuel filter. I connected the new fuel pressure gage took one reading with key on not started it was 9 psi. The second reading car started, 26 psi. Then the gage started to bounce real fast and I could not get a good reading. I turned the car off and thats the 26 psi reading I got. I started the car several times and the gage still bounced all over. I am not sure what the problem is, any help would be of help, Thanks

 

well, im not expert, but your fuel pressure is way too low. should be in the mid 40s i believe when running, not 26. most likely this is either the fuel pump or the pressure regulator. take the vacuum hose off the regulator (located behind plenum and in front of distributor), does it smell like gas or have gas in it? check the fuel pressure after the car has been shut off for an hour, is it holding pressure? if these check out ok its your pump. luckily a very easy fix in a c4

 

I do know my fuel pressure should be about 41 psi when the car is running and 36 to 38 when key is turned to on. I did check for fuel and the smell of fuel at the FPR and there was none. I thought on a 1989 vette you had to drop the tank to change the pump?. When the pressure gage was at 26 psi ,it did bleed down to 6 psi in 5 min's. That was my thought that the pump was on its last leg. Why would the pressure gage neddle be jumping up and down? Thanks for the reply.

 

nope, no need to drop tank. if you open the fuel door theres four screws that hold the door to the body (believe they are torx head) then under that there is a rubber boot that comes off and then i think 9 10mm bolts and the whole sending unit with pump comes out. theres a couple threads out there on the subject. the only reason i can think for the bouncing needles is that maybe your pump is sporadically working, constantly increasing and decreasing pressure but im sure someone has a more scientific reason for why thats happening

 

heres some pictures from when i did it on my car so you have an idea

 

A picture is worth 1000 words and Solaris_vii has this one covered.

 

where did you get that compleat asemble. and how much it cost.

because I was looking on ebay. and the have just parts. but the completed asemble look much better

 

Thanks for the pictures. I will pull my pump tonight when I get home from work.

 

An Assembly at NAPA is about $500.

I'd guess it's out of gas or the Pulsator is leaking at the seals - replacements, unless you go OEM will eliminate the Pulsator (which no one stocks anyway). In it's place, you're going to clamp a piece of fuel hose (included with the pump) to the pump and then the outlet. It's a far better deal than the OEM setup. Unfortunately, you may find that the tank gasket isn't stocked by anyone either, but if you're lucky, yours will still be in decent shape. Personally, I wouldn't use anything with rust on it. I'd also put in a new filter. If you feel there's anything in the line, replace the pump and then disconnect the filter. Clamp a hose to the line and place the other end in a coffee can. Turn on the key and it should squirt any crap into the can. Probably helps if you have an assistant.

 

Ecklers or Corvette America has the assy for $169 (pump not included).

Why buy the whole sender assy? a pump is the only reason the gauge fluxuation is so radical.

This is easy...

what you see on the gauge is what fuel is actually doing. If its steady the pump is keeping up with demand. If its dropping with rpm the pump is falling behind and the engine is using more than the pump can supply. If the gauge needle is bouncing around everywhere even at idle that indicates poor or blocked flow...only partial fuel flow is getting thru...eachj time the needle drops is an instant that the flow stops, so IF your filter is new, then your pump is bad....
Look up Racetronix and buy an upgraded pump and be done with this problem AND the next one that will appear from poor performance at higher rpm. The Racetronix pump WILL maintain pressure even as RPM increase...so there will be no fall off in pressure. maintaining the 40 psi throughout the rpm range is the secret...those that DO maintain pressure can rely upon their tune...those that have pressure drop never see what their tune/engine is capable of..because its starving for fuel at some point and that changes everything.
Get a pump.

Good catch on the needle... seeing pressure is one thing. Reading the gauge and understanding the behavior of the needle is quite another.
There is a good chance that its only the sock thats bad...but when you have to get in the tank to change a sock you change the pump as well.

Get a new tank gasket too and you might want to get several small hose clamps for fuel lines....

 

i actually bought the sender and fuel pump seperately (bought sender because gas gauge wasnt working and did pump while in there). bought the racetronix kit for the pump which is a great deal for the price and comes with tank gasket and filter sock, highly recommend it over any parts store junk (and i work at a parts store) and really havent been too impressed with delco fuel pumps either. good luck op!

 

That sounds great, I will look into getting the racetronix set up. Who might sell this kit, also what pump do you recommend.

 

racetronix is actually the people who sell it, they stock walboro pumps. they have for your car either a 190 lph (litre per hour) pump http://www.racetronix.biz/customkiti...kc=FPA-011&eq= or for $0.65 more you can get the performance 255 lph pump http://www.racetronix.biz/customkiti...c=FPA-011H&eq=. i think going for the 255 lph one is a no brainer, it will work fine on a stock car and can support future mods. comes with wiring adapter, sock, gasket, hose, two clamps, and even new bolts for the tank (i used the stock ones, im weird like that).

 

I was just on there site and that is not a bad deal at all for $ 109.65. I will be buying it tommorow. Thanks for the info and replys.

 

good luck! just make sure you order the right stuff, theres three different options for the c4 depending on the year

 

very good I like that it come with a new gasket and the screws. Ima mising one