Question: fuel pump

[English Guy]

hi folks,i'm having trouble starting 89 l98 and think it might be fuel pump.when ign key is turned(not cranking engine)fuel pump buzz's for a couple of seconds then goes quite,is this right or should it buzz all the time?thanks for any info

 

[gmjunkie]

hi folks,i'm having trouble starting 89 l98 and think it might be fuel pump.when ign key is turned(not cranking engine)fuel pump buzz's for a couple of seconds then goes quite,is this right or should it buzz all the time?thanks for any info

Yeah,It should run and then shut off till the engine is started! Should build 34-39 lb fuel pressure at key up on a L98!!

 

[English Guy]

good news hearing that!thanks junk

 

[T.M.808]

what kind of starting issue are you having?

 

[WillC4]

Well, if it does turn out to be needing a new fuel pump, give this company a look at.
Racetronix - C469 Fuel Pump Assembly - Kit Configuration Page <=Fuel pump
Racetronix - FPWH-014 - C44 1989-1996 Fuel Pump Wiring Harness <=FP Wiring Harness

They are a reputable company with affordable prices. I got a kit for my 96 camaro a while back. Good quality. I am considering getting one of their 190 lph kits for my 94 vette when i port its heads and put a cam on it.

 

[English Guy]

HI T.M.808 the car fires up but dies 1-2 seco.nds later,driving me crazy

 

[English Guy]

Thanks for the info willc4,i'll be looking them up if i need new pump.

 

[surfer93]

Check out thepartsladi on the bay, she has oem at a real good price.

 

[English Guy]

thanks surfer93,have a good one.

 

[vetteboy86]

Is your SES light on when car is running for those few seconds?

 

[John Robinson]

Keep a journal

I would suggest you keep a journal of the things you try and the results. Otherwise you will be trying to remember what they were.

I am going to suggest that you check the TPS (Throttle Body Sensor)

I have discovered that it has a hand in about everything the ECM does and thinks. It probable is one of the most involved in how the car runs.

Hope this sheds some light on the tps for you
I know it is for a 93 but the princple is the same for your car

​

Throttle Position Sensor (TPS)
Copied from 1993 Service Manual​

The Throttle Position sensor (TPS) is a potentiometer connected to the throttle shaft on the throttle body. It is a potentiometer with one end connected to 5 volts
from the ECM and the other to ECM ground. A third wire is connected to the ECM to measure the voltage from the TP sensor. As the throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also changes. At a closed throttle position, the voltage output of the TP sensor is low (approximately .5 volt). As the throttle valve opens, the output voltage should be approximately 5 volts.

By monitoring the output voltage from the TP sensor, the ECM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent burst of fuel from the injectors and cause an unstable idle, because the ECM detects the throttle is moving.

If the TP sensor circuit is open, the ECM will set a DTC 22. If the TP sensor circuit is shorted a DTC 21 will be set. A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set, the ECM will use a default value for TP sensor, and some vehicle performance will return.

A personal note, when my TPS failed it DID NOT set a code other than to tell me the ECM was bad.

I used a couple of straight pins through the wires to hook the meter on

​

 

[English Guy]

Hi vetteboy,I hav'ent a clue what a ses light is:confused.Please explain,many thanks

 

[English Guy]

Hi John
Many thanks for the detailed info, i will be giving the tps a good looking over but please could you tell me what DTC stands for?Cheers

 

[John Robinson]

DTC stands for Diagnostic Trouble Code. SES stands for Service Engine Soon The SES light if it stays on is telling you that it has stored codes for possible trouble in a given system. By pulling the codes you are accessing the DTC stored in the ECM memory.

 

[vetteboy86]

I would attempt to retrieve any codes that may be stored. It is possible that the service engine soon (SES) light may not be lit, and codes have been set.

 

[boomdriver]

Thats very possible....the C-4 was the first to have trouble code memory. It may not be indicating a current code but it will have a stored code or a history unless the memory has been wiped by battery disconnect.

 

[vetteoz]

I would attempt to retrieve any codes that may be stored.

C4 Corvette Diagnostic Code Recovery Techniques

 

[WRECKER88]

My 1989 had the same problem. First problem was the the motor died when i was driving. After i towed it home i found 12 volts to the pump but it was not running. I replaced the fuel pump, strainer and the fuel filter. The car would start run a short time and shut down. I was told to check the injectors for shorts.The #7 injector was shorted (3.2 ohms should be 16 ohms). I reconnected all but # 7 injector and now the motor runs and does not shut down. So now i going to order and replace all 8 injectors.

 

[vetteoz]

The #7 injector was shorted (3.2 ohms should be 16 ohms). I reconnected all but # 7 injector and now the motor runs and does not shut down.

If one injector is shorted the computer will shut down all the injectors in that bank so you will be only running on 4 cylinders

 

[boomdriver]

Exactly...
Something that many L-98 owners do not know, is that
ALL injectors on one side operate at the same time, together. In effect, there are only 2 injector circuits on the L-98 C-4 even though it has 8 injectors. Short any injector and its like killing that side of the engine. Some shorts can lead to the whole set being stuck Open, flooding the engine with fuel.
So, the L-98 is not all that far from the crossfire in evolution.