CTSV_510

iTrader: (1)

I have had a slight starting issue for a while now...the fuel pressure at start-up wasn't holding so I have had to run the fuel pump twice before starting. Turning the key to the on position runs the pump for 2 seconds, then a switch to off and then to start and it would start fine. Since I NEVER had any fuel leaks, I suspected a faulty check valve in the fuel pump assembly (after consulting the service manual.) Well I kind of learned to live with the issue since dropping the fuel tank @ 10 or whatever hours of labor would be awfully expensive to fix something that was little more than a nuisance.

On Sunday I was running around town doing errands, then I stopped at the gas station on the way home and filled up the tank. When I got home and got out of the car, there was a pretty strong smell of gasoline. I looked under the car and found this:


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Holy crap that was the first time I'd seen anything like that. I threw a catch pan under it and then jacked up the passenger side of the car until the flow stopped. I inspected for damage but saw none. The leak was obviously coming from the top of the tank, which is absolutely impossible to see or even reach with your fingers. I lowered the car back down and the fuel started spilling out again. 30 minutes later and a full gallon had drained out. I ended up jacking up the drivers side next to try to get as much drained out as I could and got about another gallon.

I searched and found just one single forum member that had the same issue. I contacted him and found out that he ended up cutting a hole underneath the passenger side rear seat right above where the leak seemed to be coming from. Much easier than dropping the exhaust, driveshaft, and rear subframe to lower the tank. His issue was a loose locking ring that holds in the fuel pump assembly. He was able to simply tighten it back up, button up the hole and move on.

I wish my issue was that simple. After cutting a small hole and looking around, it wasn't obvious where the leak was coming from because the locking ring was definitely fully locked. I reconnected the battery and turned the ignition to on while me and my buddy watched for a leak. Immediately, smoke started flowing out of the hole so I shut the ignition off and disconnected the battery. We opened up the hole more, here is a shot looking from the passenger side into the car at the top of the fuel pump assembly:



Looks OK from here. Now from the other side....


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YES, that is a hole burnt right through the electrical connector piece that comes out of the top of the fuel pump assembly.

I believe I am pretty lucky to have not blown up in the car at some point in the past year or so. Now, WHAT THE HECK CAUSED THIS????

I have a maggie with a magnavolt (Magnuson brand fuel pump voltage booster) that I have been running for 18000+ miles. My buddy and I went back over the entire installation of the magnavolt system and how it ties into the fuel pump curcuit. Everything is exactly as specified in the manual, with the addition of the extra ground connections to prevent the magnavolt from burning up, which was a very common problem. The original fuel pump fuse gets changed from a 20A to a 30A when installing the magnavolt.

Now I KNOW I have never read about anyone having this issue anywhere on this forum or ls1tech. It doesn't seem that the magnavolt is to blame because there are people out there that have run them for a whole lot longer than I have with no issues like this.

My buddy works at a corvette shop and has a line into GM so he is ordering me a new pump tomorrow. I still need to figure out WHY this happened so I can make sure it doesn't happen again.

Maybe the starting issue I've had (mind you this is the only odd symptom I've had, the car runs flawlessly otherwise) was actually my fuel pump going bad? Could a dying pump cause this piece to burn up somehow? I bought the car used with about 36k miles on it 2 and half years ago so who knows what happened to it before then. As long as I've owned it I never ran out of fuel, which I hear can cause damage and shorten the life of a fuel pump.

Any help or ideas is appreciated!

Tom

killernoodle

GM fuel pumps blow hard.

That could have probably started a fire given the right circumstances.

itsslow98

iTrader: (18)

I hope your not going with another factory pump. While your in there id do a walboro or something.

Glad your ok that could have gone real bad real fast.

Stepside

I seem to remember reading something about an internal bypass in the tank.
For your fuel pump to fail would mean:
1. It's a Mfg. Defect?
2. It's a connection defect causing high resistance which equals heat?
3. Your pump is working harder & longer than it's engineered too, because of 'another' 'pre-existing condition' of the operation of the system?

Your approach to this appears to be methodical & logical and should be commended.
You are correct to find the exact cause. It would be terrible to replace the pump and have this happen again. I wonder if anyone in GM Engineering Department is driving a V1. Shoot them an email.
Those pictures are soooo, scary!!
Keep us updated . . . good luck.

JJSimon904

iTrader: (8)

I showed this to a buddy and he said his 4th gen about caught fire the same exact way. That connector shorted out.

Slithering_Joe

Tom, you're lucky that car or you didn't burn to the ground.
Since the Boost-A-Pump runs the factory fuel pump at 17-18V under boost, don't you question that maybe that elevated voltage (& current) roasted the connector?

maxspeed05V

iTrader: (4)

WOW is all I can say, good luck 154

raven154

iTrader: (14)

You mean 510?

greddy91

iTrader: (2)

That solidifies my decision to use an external walbro - no magnavolt for me.

However - can you take pics of the exact geometry and placement of this hole? I'd consider cutting on her and making a trap door if I could put an in-tank 255 in.

liqidvenom

iTrader: (2)

that really blows man. i still dont understand why there isnt a door to check the fuel pump without having to lower the entire tank.

CTSV_510

iTrader: (1)

Yeah I know. I do question the elevated voltage, but if the magnavolt is working properly it should only be boosting occasionally and it doesn't seem to have been a problem for anyone else. I do question whether the magnavolt is working properly though - its possible it is malfunctioning and boosting all the time, which would be a better explanation.

Sure, no problem. They should have built a trap door from the factory, but like my buddy said, what would X number of trap doors and X number of screws cost GM to do that? Too much I guess was the answer.

CTSV_510

iTrader: (1)

I actually can't believe my fuel pump was still working :



The fuel pump lock ring is a pain in the *** to get off without the special GM tool.

JJSimon904

iTrader: (8)

If they had trap doors, then they couldnt charge you $1000 to change your fuel pump!

Yes it is..lol

CTSV_510

iTrader: (1)

A 10" section of copper pipe (no sparks) and a mini sledge hammer finally got the lock ring loose. Tomorrow we'll replace the pump & assembly and wire in a new pigtail connector and get it running again.

greddy91

iTrader: (2)

Pics of the door for measurements and location when you get a chance please.

GRACIAS!

wkdivr

iTrader: (8)

You might want to install a fuel pump hot wire kit while you're in there. From the looks of your plug, I think an f-body kit might do the trick.

xxrillixx

iTrader: (118)

wow, i cant believe that didnt start a fire. It wouldnt blow up, but it sure as hell could have caught fire and burned down in a heart beat.

The fuel was coming out of that hole? Seems odd that you lost a full tank of gas from the top of the tank... Does it not sit parallel with the ground?

I ask because getting fuel into the connection could cause it to burn up like that. I wonder if you dont have a leak somewhere else that got the connector wet causing it to burn up.

CTSV_510

iTrader: (1)

To start the hole, use a regular drill with a drill stop on it so that it can only go down about and 1/8" just to get through the sheet metal. You don't want to go too far because you could damage the electrical wiring, sending unit or the tank itself. This picture is looking in from the passenger rear door at the area below the rear passenger seat:



I cut the hole out with tin snips - the metal is very thin and very soft so it was very easy. The lock ring that holds the fuel pump assembly in is a pain to get off. I cut the hole a little bigger at the top of the picture to get a 10" piece of copper pipe at a good angle on the ring to break it loose. Use a big hammer for this - I used a mini sledge and you have to whack it really really hard or you're wasting your time. You will see that I cut the plastic fuel line connection because I was replacing the whole assembly. If you're re-using these parts, you may have to cut the hole bigger in a different spot to get a good angle on the lock ring.

CTSV_510

iTrader: (1)

What is a fuel pump hot wire kit?

I didn't lose a full tank through the hole; it drained about 1.5-2 gallons before it stopped leaking. The hole had to come before the fuel leak because that area is totally sealed. We inspected it and there is no where else the fuel would have come from. With the new parts in and everything back together and operating, there are no leaks.

raven154

iTrader: (14)

Hot wire kit is basically running a new fuel pump wire and adding a relay and using the old fuel pump wire to trigger the relay. It goes from am 18awg to a 12awg wire. Not a bad idea but it doesn't seem this is as much of a problem with the wires being able to handle the load as it is the connection just built up a lot of resistance and got too hot.