sycklylow

I have a friends 93 vette and it ran like crap when i got it and barely would stay running, i changed the water pump for him because it was leaking and decided to look into it further, the plugs were fouled and one was broken in half, the wires were shot as well. i replaced the wires and plugs with all new ac delco and now it will fire right up and idle like a new car. if i hit the throttle it almost stalls, if i ease into the throttle it revs until about 1/4 throttle. when i put it in gear it almost dies too but it will idle ok with the brake on. ive been told by a couple friends to check the map sensor and coolant sensor because they deal with fuel and air metering. the car sat for about 6 months and had a fuel pump put in it before it sat. anyone have any ideas?????

aminnich

Scan it for codes. It does sound like the opti, but that is just a guess based upon the leaking water pump and the symptoms you have described.

daniel5625

im guessing the opti also, because the water pump was leaking, it probably leaked onto to opti and ruined it. they are very sensitive to water.

dizwiz24

Optispark

sailorsteve

I agree that a scan for codes should be the first thing you do. The opti is expensive and a pain to install, so don't install parts you don't need.

surfer93

Everybody said OPTI, but this a classic fuel pump going south problem.
Put guage on the car and watch the FP and see what the pressure is when the engine stumbles.

Also, did you clean the inside of the opti cap or look inside?
When my 2nd WP dumped onto the opti, my ran like junk and I cleaned the cap w/electrical cleaner and car ran normal again.
But mine would barely idle and that your friends idles great, leads me to believe you have and air leak(s) or fuel problem.

MikeSVO

In addition to the other things mentioned, I'd also check out the rubber tube that connects the air filter housing to the throttle body, just to see if it's collapsing once you open the throttle. I just checked mine out for the first time, and it was sort of folded over where the hose clamps are (on both ends), and looked like it had been that was for a long time (I just got the car, so I'm still checking stuff out). Also, I don't know if these have mass air meters, but if they do, make sure that's working. When we forget to re-connect those on our Fords, they do the same thing.

Lrod

Throttle Position Sensor defective?

C4happy

TPS bad run a scan tool check voltage when moving throttle

sycklylow

i borrowed a fuel pressure tester and checked it, it was 0, didnt even read anything. i pulled the fuel filter and couldnt blow through it so i changed it and checked the pressure again. it still reads 0, i think i can hear the pump running but the gauge has a pressure release button to allow fuel to go through the gauge and into a bottle or whatever. when i press the button nothing flows through so i guess it could be the pump even though i think i can hear it???? how do i access it also?

steverichmond

Does this help?http://http://www.joby.se/corvette/mods/2001-0X07_fuelpump/

MickPB

Check the easy stuff first - Pull the FPR and put some air to the side that goes in the fuel rail. Should hold 40 with no leakage. Sometimes you can hold it in front of a bright light and see straight through the diaphragm.

sycklylow

i pulled the fpr off and it looked all rusty and grimey. i cleaned it out and when u hold it up to a light and look from the fuel line side out the vacuum side i can see light like its through a transparent paper, is that what you were talking about mick? and is there a different way to check it? i saw what looks like a aftermarket fuel power supply and i asked the owner of the car and he said it was on there when he bought it so he has no idea what it is.....any idea where something like this would be ran to?? i found the power wire and ground but there is a bigger line coming out. one runs down the driver side and one to the passenger side.

94vettelover2

Sounds like you have a defective fuel tester gauge.If the car idles there will be fuel pressure.Get another gauge to see if it reads different.Replace fuel pressure regulator if rusty.While reving up car monitor fuel pressure-fuel pressure should increase while reving engine.Pull off vacuum hose that goes to fuel pressure regulator.Fuel pressure should increase around 10psi.Hook up a scan tool to check for codes.Also check the datastream for abnormal readings.Check TPS voltage while key is on,not running.Slowly press down throttle watching TPS voltage to see if it increases gradually.You can do this test & MAP test with a volt meter if you have no access to a scan tool.Check Youtube.You can also check for codes with a paperclip.Also won't have been a bad idea to check for good spark at all plugs as well as ohm each injector.You can take a screwdriver & put it on the body of each injector & put ear on handle while car is running to see if you can hear each injector firing

sycklylow

i checked the tester on my truck which verified it worked properly, the car will not start and run, i believe the fuel pressure is the problem being it has 0 key on and when cranking, i can hear the fuel pump running for a few seconds when the key is turned on so i would assume the fuel pump is running, just nothing getting to the injectors....will a faulty fpr cause no pressure all the time??

MickPB

If you have an air compressor put a drop of oil on the vacuum nipple and then put 40 psi to the fuel rail side of the regulator. IF the oil comes back up the regulator is shot. If you dont have an air compressor --- I have been told you can crimp off the return line back at the filler for the tank and build some pressure that way but --- I wonder about what that does to the pump --- Your choice but .... IF you put a new regulator in it -- Spend 10 and get a filter too

sycklylow

found the issue with the fuel pressure, the sending unit is shot and it showed 1/2 tank and it had no gas in it. I took the pump out and it was rusty and shot so i replaced the pump and strainer and now i have proper fuel pressure but it runs like **** now, it has a map sensor code (#34) so i guess thats my next step, any ideas for this ??

sycklylow

changed the map sensor and still runs like crap, it will fire up sputter then stall out in a few seconds....

sailorsteve

If the fuel pump you took out was rusty, the fuel filter may be clogged with rust, enough to keep the engine from running more than a short time.

surfer93

Map sensors rarely go bad, check the wiring for breaks and bad connection at the connector.

Disconnect connector, jump all 3 wires. Then connect a voltage meter to B(Lt green) and C(gray) w/ignition ON. Voltage should be over 4.7, if it is not, then the sensor is bad or there is broken or frayed wire.

Check the ground wire(black) for breaks along the entire route from MAP to IAT and AC.

If all check out, then check ECM pinout for bent pins or bad connections, if they check out, then it is most likely a bad ECM or bad vacuum leak.

Trust me, I have a 93 and had a 92. I am on my 3rd ECM on mine. Tell the owner to fix codes immediately, as a bad sensor left to long will kill a ECM.