My big fuel pump mystery / problem.

Wall of text incoming! :D

So last night I replaced my fuel pump for the 3rd time. The other 2 went out on me, not sure why but I am thinking its because I ran it with low on fuel and it possibly seized or something. (Im not really sure if thats possible, just an idea) But last night I replaced it again (I am using walbro's, the other 2 pumps were walbro's also).

On the drive home the car stalled out about 50 yards from my apartment complex (My guess is from fuel as there was only about 2 gallons in the tank.) But I was able to start it back up by popping the clutch when I was coasting very slow. I parked it and went to a friends house to help him find a boost leak.

This morning I go outside and see if it starts up, It gets a few chugs and then just cranks. Turn the key back, turn it back on, few chugs and then crank crank crank. WTF I tell myself, this is a brand new pump installed last night. Hmmmm

So on that note, would anyone have the slightest idea of what is going on? Is it that I am messing up the pump by only having 2 gallons in at the time? Or am I just cursed with bad luck?

Any information would be helpful as I am moving at the end of the month and my car needs to make it to my new place and my job once my carpool buddy resigns.

Thanks in advance guys.

is it hotwired? maybe your wiring is bad and frying your pump? Have you confirmed it is infact the pump?

I don't have it hotwired. And I haven't even had time to really check. I am just guessing its the fuel pump as it seems to be the same symptoms as the last time it died. Also the car mods just for note are bpu at best. Just trying to get some ideas on what to check for when I get home from work today.

(Also the reason I think of the low fuel thing burning up the pump is because this has only happened when my low fuel light was on)

When you replaced your last pump did you apply power directly to the last pump to see if it was working? Maybe your problem is not the pump but the relay or resister thingy [sorry can't remember the correct name lol]. I would do the hotwire and try again.

I will go with the hotwire idea and see if that helps. But would you have any other suggestions before I spend the money? (Basically broke until the 15th =(, Damn stage 2 heads and security deposit)

You can do the resistor bypass with will cost you like 5c LOL this will bypass the low voltage setting for the pump and run it at full power 100% of the time. However it will still use the stock wiring. You need to do the bypass for the hotwire anyway so start with that. Otherwise get someone to crank the car and listen to the pump. It's a Walbro so you should be able to hear it even when cranking. If it's running then your problem could be something else. Check spark? There is also a way to measure fuel flow by removing the fuel line off the regulator and cranking for 30 seconds and measuring the fuel that comes out in a jug which will tell you if it's flowing enough. However I cant remember the formula for this. Obviously this will only work if the pump is running hahaha.

I will remove the high pressure line and see if anything comes out. I may rewire the assembly and see if that helps. I honestly wouldn't care about the problem as I am in the progress of a build for it, but it is my DD right now. :facepalm:

Bumping this for anyone else that might have information to add or another idea. I took the rest of the day off work to figure this out. So any other help our thoughts on what might be the issue would be nice. I am going to start working on this soon.

MFI relay?

Low fuel is not your problem. 2 gallons of fuel is more than plenty to keep the car running. I've put 19.5 gallons in the Stealth before and it only chugged and almost died on a sharp curve once.

As has been previously mentioned you need to do real diagnostics before you keep throwing parts at it.

I pulled the pump, rewired it to the bulk head. Hooked a fuel hose up to the out going line on the pump and nothing came out during the cranking. It sounds like the pump is spinning really slow. I am looking up the relay info right now.


EDIT:

I went and followed this http://www.stealth316.com/2-fuelpumprelaybypass.htm Nothing changed, the pump still sounds the same. I will take a break from it tonight and go BBQ some food. Get back at it tomorrow.

And I wouldn't say I am throwing parts at it. When I said I went through 3 pumps that is in the lift time I have owned this car. 1 is the stock pump, the 2nd was a knock off walbro and the 3rd was a used walbro to get the car running (lasted longer than I thought) and now I am where I am at. Seemed logical to buy a pump since the last one stopped flowing.

On that note, anyone want some BBQ and beer?

You get what you pay for. Don't buy cheap knockoff performance parts or used parts for critical components. 9 times out of 10 there's a reason why someone is trying to get rid of them.

Buy a new pump and doublecheck the wiring to make sure it's been installed correctly, also check and make sure none of the wiring posts on the hanger are damaged. I've literally seen the posts snap which can result in shorting the pump in the gas tank (which is a bad thing).

A few other things to note... Do you drive with your gas light on often? High flow pumps get really hot and need adequate fuel levels to keep them cool so they don't overheat. Second, the gas tank also needs to have adequate ventilation so as not to turn the gas tank into an oven. If you've done a vac reduction and have the tank vent blocked it could lead to problems in the long run.

Cheers.

Jeremy

Actually there is a fuel pump diagnostic port in the corner near the firewall [pass side for UDM market] which allows you to power up the pump. I believe it's the blue connector and you just jump the 2 pins to create a circuit..... check your sevice manual first though to make sure that's correct.

Steve - do you know the formula for the fuel flow calculation cus I posted he same suggestion above but don't know the correct flow rate.

LOL didn't think of that hahaha

Its probably the pump just replace it. I went thru the same issue but had a Denso Supra and felt it could not be the pump and replaced relays 3 times and somehow it would work for a little while and the relays did go bad for some reason. The pump ended up failing for good after a year or two of this.

Sam

I emailed them, hopefully they get back to me soon. But I did end up modifying the fuel pump housings bulk head which I think is pretty cool now. I think I can fully swap my pump in 8 mins now.

As for the formula guys, all you have to do is get your L/H and divide by 60, then half it for a 30 second cranking time at full voltage. Pretty simple lol.

I would say your pump is probably shot, try the new Aeromotive pump with the hotwire kit, I hear very good things about them!