how do u know fuel pump is bad??

Post by **nissilvat** » Fri Apr 22, 2005 2:29 pm

hey-- ive been havin the same problem w/ my 240 for a while now ( ka-e ). it used to not happen that often but now its real bad. see when the motors cold it runs great, but when i gets to normal operating temp is when it happens. when i come to a light i have to hold the gas down to keep it alive, whenever i drive it after its warmed up i cant hold the gas constantly i have to feed it, then let off, cause if i hold like a normal car, it starts jerkinng and sputtering, like the catalytic converter is clogged, but i got a magnaflow high flow cat, and still the same, so..THE QUESTION IS , IS IT MY FUEL PUMP??? how do i test it to see if its messed up???? my car is suckin a lot of gas cause of this. i get about 150 miles to a tank every week, usually between 137-160 from my tank.HELLP GUYS!!!

sorry for the long post

Post by **NateDogg** » Fri Apr 22, 2005 5:00 pm

Sounds like your O2 sensor and/or Coolant temp sensor is DONE. If you haven't done any maintenance I would start checking those sensors for abnormal readings. If you dont have a FSM you can check out http://www.zeroyon.com and dl it there IIRC...

Post by **benemorius** » Sat Apr 23, 2005 5:51 am

Yeah I'd start checking sensors. I've seen a fuel pump behave somewhat like that on a Ford Ranger but...

If it were the fuel pump, the O2 sensor would likely read leaner than normal once the engine gets warmed up and starts having trouble. Maf, tps, O2, and coolant temp are the first sensors I'd check. It could also be some emission or other control device messing up. Aiv, egr, iacv especially.

Post by **nissilvat** » Sat Apr 23, 2005 11:32 am

ok benemorius, i think my maf is bad cause the metal clip that holds the plug in the socket is gone and since one motor moutn is a little soft it jerks that plug around , i know that much, but if i took itsomewhere and had them plug it in( diagnostic ), would they be able to see any codes related to those sensors? BUT since it only acts like this when the car is warmed up, i dunno. but i did change the coolant sensor thats right on top of the motor, in front of the injectors( the one with the sticker that says"dont open when hot", but are there any others???? thanks for your help man.

Post by **benemorius** » Sat Apr 23, 2005 12:08 pm

The metal clip is good to have, but the plug should at least be able to keep a good connection for a while. Clean up any filth on the connector, bend the metal contacts if necessary to make good contact, check to make sure nothing is corroded, and try hooking it back up.

Your engine is OBD-1. The computer will basically only say that something is wrong if something is VERY wrong. You can even unplug many sensors and OBD-1 won't give a flying rats ***. You're going to have to figure this out manually.

The coolant temp sensor you replaced is the only one that the ecu cares about. The other one just goes to the temp gauge in your dash.

What you need to do is go to Sears/RadioShack/Walmart and pick up a multimeter. They vary in price and functionality but you can get a $15 one and it will do fine for this kind of stuff. Search the forums for information on testing those sensors I mentioned. This is the only way you can know for sure if a sensor or it's wiring is acting up.

Post by **Marshalarteest** » Sat Apr 23, 2005 2:03 pm

get a fuel pressure gauge then test it off the hose from the fuel filter to the fuel rail. when u turn to key on engine off it should read about 46psi, and if u run it idling it should read around 36 psi. but like everyone said its probably not your fuel pump doing this cuz when fuel pumps die your car usually never starts up.

Post by **Marshalarteest** » Sat Apr 23, 2005 2:06 pm

oh and you should really check your coolant and maf sensor circuits, probably better off going to an electrical shop if you don't have any experience with it. those two are in the top 3 most important sensors and theyll cause your car to be fuuuuucked.

Post by **NateDogg** » Sat Apr 23, 2005 2:42 pm

You didn't replace the coolant temp sensor. You replaced the rad cap (from your description).

The CTS is beside the rad hose on the intake manifold and is usually red with 2 wires coming from it.

To test

COOLANT TEMP SENSOR:Take off the connector and tap the two wires with an ohm meter. It should read .3-.33k ohms at operating temperature (engine hot). If it is more, you will be using more fuel. If its in that range, it's fine. Clean the connections.

O2 SENSOR: To check this, you have to have a factory service manual. Download it. Then do the diagnostics like the manual says or do a search for instructions here.

Honestly, it sounds like a combination of the two AND possibly a bad ground at the back of the head to the firewall. Make sure they are bare metal, clean with no grease!! Oil leaked from the VC to that ground on my car and caused a stumble which I fixed today.

Good luck.

Post by **benemorius** » Sat Apr 23, 2005 3:51 pm

He did replace the coolant temp sensor. On the sohc (dunno about the dohc...) it happens to be right next to the coolant burp plug, which has the warning that he described right by it. And yeah - it's right in front of the injectors.

Post by **nissilvat** » Sat Apr 23, 2005 6:51 pm

no i did replace the temp sensor, it had a red hat like a injector, and a copper rod extending from it, i know that much. it was directly left of the valve cover if u are standing at the front of the car.

Post by **nissilvat** » Sat Apr 23, 2005 6:55 pm

ok everyone thanks for everything, but this problem affects the car majorly. it surges and sputter really bad. even if you press the gas hard, it justs jumps and pauses bad. i need to pull the plugs and check em. and also get new spark plug wires and maybe a ground kit. ill see if that works.

Post by **NateDogg** » Sat Apr 23, 2005 8:26 pm

My bad but read my post about the ground wire. You will kick yourself if you keep buying stuff and it doesn't fix the problem.

Post by **nissilvat** » Sat Apr 23, 2005 8:32 pm

aight thanks dude, iam gonna try everything tomarow, i hope i can find something that works, cause i dont wanna keep ****in with it for to long

Post by **jsicolo** » Tue May 31, 2005 7:43 pm

Hi, I am having the exact same problem right now with my 92 240SX, 5spd, 137K miles. When the car is cold, it runs great, but once it warms up, it bogs down on acceleration, like its not getting enough fuel or something. It also surges too. It can cruise ok on the highway around 3000 rpm, once it gets up to speed, but any type of hard acceleration, causes bogging.

The first thing I changed was the plugs, and it didn't solve the problem but it made some difference. The car had alot more power, and I didn't have to put it in neutral and gas the engine at a light.

The problem is still there though. Next I tried the air filter, fuel filter and O2 sensor, with no difference. Also, I have been adding fuel system cleaner each time I fill up, and that doesn't seem to be helping either.

I guess I will try checking out some of these sensors the folks mentioned here.

I was reviewing some of my servicing, and it looks like the PCV has never been changed. Is this important??

Thanks, and good luck! Jim

how do u know fuel pump is bad??

how do u know fuel pump is bad??

Re: (NateDogg)

Re: (nissilvat)

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Re: = (Marshalarteest)

Re: (NateDogg)

Re: (NateDogg)

Re: how do u know fuel pump is bad?? (nissilvat)

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