car won't start(turns over)

[vancouverbc]

re 1991 240sx

turns over but does not start. jumping battery did not help. gas tank quarter full. fuel filter ,starter, and alternator no more than year old. very rarely, car does hesitate for an instant when going up big hill. car does stall quite a bit when idyling at stop sign. first time i have not been able to start and happened in remote area:(

[vancouverbc]

Went outside 4 hrs later and car now starts. the outside temp is about the same as 4 hrs ago when car would not start. i'm pretty sure it was not flooded. i left it for .5 hr and it still did not start.

[NISTECH]

next time it happens hold the pedal to the floor and see if it will try to sputter to a start. If it does that means it was flooded. In that case check your coolant temp sensor for corrosion. Its the 2 wire red connector near the front of the intake manifold.

[vancouverbc]

Thank you for response. I did put pedal to floor but with no effect.

If this happens again, is there something i can spray in carb etc to get car going assuming it is a fuel problem?
Modified by vancouverbc at 10:48 PM 4/13/2005

[vancouverbc]

While looking for fuel pump, i did notice that it is damp in the corner where fuel pump trap door is located. Water is leaking in from outside through hatchback door. The trap door for fuel pump is not sealed.

[NISTECH]

is there water in the connectors for the fuel pump? If so I bet thats your problem.

[vancouverbc]

it didn't start again and it is dry today. i don't hear the fuel pump noise so i guess it is the fuel pump. i got 12 volts with voltmeter between some terminals. connecting to one terminal i would only get 7 or 5 volts. i tried every combination at random so i don't know if the 7 volts suggest a problem with power at connector.
Modified by vancouverbc at 2:47 AM 4/15/2005

[NISTECH]

where did you test it? and where did you find 7 volts?

[vancouverbc]

i did not get 12v at black/yellow and ground even in first 5 seconds of ignition being turned on. red and green wire seems to be related to fuel gauge in instrument cluster. Should i hook fuel pump up to 12volt source to test it? Is the fuel pump relay right next to battery in a unit with eccs relay? a plug rather than conventional relay?

I tested the connector right at the fuel pump. There are five wires coming in. between black/yellow and green there was 7.4 volts. also 7.4 volts between black and green. only 4.5 volts between green and red/black.12volts between red/black and black/yellow. 12 volts between red/black and black.

Modified by vancouverbc at 6:38 AM 4/15/2005
Modified by vancouverbc at 10:24 AM 4/15/2005

[NISTECH]

the lower voltages are likely the inputs to the cluter for fuel level and low fuel light, step back a second and do something a little more basic, hook up a feul gauge and see if theres pressure or not. if there is no fuel pressure when the car is cranking have someone bang the fuel tank palm slap works pretty good if all the sudden your pressure builds and the car starts you found it. your pump intermittenly is going open circuit probably due to bad contact with the brushes in it.

[vancouverbc]

hitting the gas tank did not do anything. i hooked up 12v to fuel pump harness (positive to black/yellow, neg to big black wire) for instant and got a short(fuel pump fuse blew). positive to all the other terminals did nothing.bought new fuel pump for 180 canadian at Lordco. plus strainer for another 20 bucks.
Modified by vancouverbc at 1:29 AM 4/16/2005

[NISTECH]

if you applied voltage to your other terminals it is very likely you smoked something. You cant just start throwing voltage into wire harnesses likel that.

[vancouverbc]

Installed new pump and car starts. after removing pump it is easy to test. only a positive and negative terminal. old pump did nothing when hooked to 12volts. I traced the wires and i was using the right wires all along so i don't know why i did not get 12 v at pump harness (in first 5 seconds)or why i got sparks when testing old pump. pink/white from pump assembly is positve side of pump and goes to black yellow on connector. blue/red from pump assembly is negative of pump and goes to large black wire on connector.

Notes:

1. if testing pump outside of tank, only apply power for instant.2.buy a strainer when you buy new pump(o-ring too)3. be careful not to bend float when removing pump4. don't overtighten screws holding pump assembly to gas tank(6)5. i had no problem disconnecting rubber outlet/inlet hoses to pump assembly. i think key is not to grip rubber hose where it has slid over the metal tube. to remove just push hose end with pliars.

Thanks for the help:)

[vancouverbc]

I banged my old fuel pump and now it works. I retested black/yellow wire going to fuel pump and it now reads 12 volts to car ground in first 5 seconds. hope i have not replaced wrong part. time will tell.

[NISTECH]

banging the pump to get it to work just verifies it has a poor contact internally and it was likely the problem. I am more concerned with your other circuits when you jumped power to them.

[vancouverbc]

the reason i was careless in applying power to fuel pump assembly was that i was thinking it was isolated from rest of car since harness was disconnected. i was thinking i was replacing entire pump assemble, not just pump. Very faulty thinking. I was surprised when i blew the fuel pump fuse. Everything , including fuel gauge, seems to work at this point:)

[Skinsk]

I have a similar problem except I've already replaced the fuel pump and still get nothing, I thought it was the distributor so I "borrowed" another one from work and tried it. It heated up to normal temp then when I tried to move it, it just died

Yep I've got problems93 240sx