You wont be able to hear the pump with just the key turned on because it only runs when the ignition is going, use a timing gun to check your ignition because the first thing i would suspect would be the ignition module or coil, do a search for the HEI mod. The modules are a common problem but i havent heard of much people having problems wth the fuel pump
Possible fuel pump issue
Well I went to start my car a few days ago and it refused to start. It was fine the night before and the starter is going as normal but no ignition. Now I have already ruled out the basics (fuses are intact, spark plug wires are connected, fuel in tank) so now I am looking at the fuel pump as being the cause. I can't hear anything from it when I turn the key so I am assuming it is either dead or just lost connection. So here are my questions:
1. Are there any other causes I should be looking at?
2. I don't have my Haynes manual on me, does it require dropping out the entire tank to reach it? If so, any special tools required?
3. If I do have to replace the pump, is a Walbro 190lph a good choice? Will I need tuning/extra gaskets/filters etc?
I'm a bit of a novice but I will have more experienced help for the actual installation, I just want to get a good idea of the problem so I can get parts if needed. Thanks!
1. Are there any other causes I should be looking at?
2. I don't have my Haynes manual on me, does it require dropping out the entire tank to reach it? If so, any special tools required?
3. If I do have to replace the pump, is a Walbro 190lph a good choice? Will I need tuning/extra gaskets/filters etc?
I'm a bit of a novice but I will have more experienced help for the actual installation, I just want to get a good idea of the problem so I can get parts if needed. Thanks!
1 - 10 of 10 Posts
Yep. To check if the fuel pump is working, open the little black box next to the battery, marked "diagnostic", and use a paper clip to connect the FP and GND pins (there's a diagram under the lid of the box), then turn the ignition to 'on', and you should hear the fuel pump running.
But a spark problem is more likely. If you don't have a timing gun, remove one spark plug (or use a spare plug), connect it to the wire, lay it on the block (to get a good ground) and watch the spark plug while a friend tries to start the car. If there's no spark, the problem is probably the distributor. (Though it might be the crank position sensor.)
What year is the car?
Edit: I just checked your profile; it's a 93 V6, so it can't be the crank position sensor (the 93 will run even without that sensor).
But a spark problem is more likely. If you don't have a timing gun, remove one spark plug (or use a spare plug), connect it to the wire, lay it on the block (to get a good ground) and watch the spark plug while a friend tries to start the car. If there's no spark, the problem is probably the distributor. (Though it might be the crank position sensor.)
What year is the car?
Edit: I just checked your profile; it's a 93 V6, so it can't be the crank position sensor (the 93 will run even without that sensor).
Thanks for the replies, sorry I guess I left out the most important part that makes me think it is the fuel pump: the gas gauge is reading completely empty even though I have added ~5 gallons after this started happening. If I try to start it for a bit (~15 seconds) shouldn't I be able to smell gas if it is being pumped in? I know that is a rather crude way of doing it but, if gas is reaching the engine, it has got to go out the exhaust afterwards, right? Does the broken gas gauge lend itself towards another cause?
The only relation between the gas gauge and the fuel pump (that I can think of) is that the wiring to both run together (at least where the wires enter the fuel tank). Maybe the wires have become cut or disconnected? But that is unlikely to happen. I don't think they share a fuse (I could be wrong).
The only way to access the fuel pump (and the gauge) is to drop the tank, which is a lot of work. It would be much simpler to connect the FP and gnd pins in the diagnostic box, then listen for the fuel pump.
It is also much simpler to check the spark.
The fuel pump gets its signal to start running from the distributor. I am not 100% sure on this, but maybe a distributor failure could be causing no spark and no fuel. The only way to tell is to check spark, and connect FP and gnd to test the pump directly.
One other very quick and easy thing to check: open the oil filler cap and watch the cam gears while a friend tries to start the car. If the cam gears don't turn, your timing belt has broken, so no spark and no fuel (because the distributor isn't turning)!
The only way to access the fuel pump (and the gauge) is to drop the tank, which is a lot of work. It would be much simpler to connect the FP and gnd pins in the diagnostic box, then listen for the fuel pump.
It is also much simpler to check the spark.
The fuel pump gets its signal to start running from the distributor. I am not 100% sure on this, but maybe a distributor failure could be causing no spark and no fuel. The only way to tell is to check spark, and connect FP and gnd to test the pump directly.
One other very quick and easy thing to check: open the oil filler cap and watch the cam gears while a friend tries to start the car. If the cam gears don't turn, your timing belt has broken, so no spark and no fuel (because the distributor isn't turning)!
Couldnt have said it any better do what ^ he saidThe only relation between the gas gauge and the fuel pump (that I can think of) is that the wiring to both run together (at least where the wires enter the fuel tank). Maybe the wires have become cut or disconnected? But that is unlikely to happen. I don't think they share a fuse (I could be wrong).
The only way to access the fuel pump (and the gauge) is to drop the tank, which is a lot of work. It would be much simpler to connect the FP and gnd pins in the diagnostic box, then listen for the fuel pump.
It is also much simpler to check the spark.
The fuel pump gets its signal to start running from the distributor. I am not 100% sure on this, but maybe a distributor failure could be causing no spark and no fuel. The only way to tell is to check spark, and connect FP and gnd to test the pump directly.
One other very quick and easy thing to check: open the oil filler cap and watch the cam gears while a friend tries to start the car. If the cam gears don't turn, your timing belt has broken, so no spark and no fuel (because the distributor isn't turning)!
Well I checked the FP ->GND with the key turned and no sound so I think that pins it on wiring (unless FP and fuel gauge went out at the same time). Considering the fact that it was perfectly fine that night and then broken in the morning I'm betting that something furry found some tasty, tasty wiring. Are there any voltage/continuity points that I can check to see if the wiring is gone?
Yep the pump is definitely dead. I'm looking at Walbro for a replacement. Looking at this website Lightning Motorsports - Walbro 93-97 Mazda MX6, 626 In-Tank Pump Kit - do I need 190 or 255 lph and does the HP matter?
Final note on this: squirrels suck. That's right, something small and probably furry crawled on top of my fuel tank and chewed the hell out of the wiring on the tank side of the connector. This was definitely the cheapest ending to the story, so I guess I can't complain. Thanks for the other tips but I think the combination of pump and fuel guage dying at the same time was the most important clue here.
heyt at least it was a cheap fix!
1 - 10 of 10 Posts
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