Fuel starvation!

[Marx]

Hi guys, Just bought another caddy with a 1900 gti engine. Everytime you turn right it starts to cut out and i think this is where the fuel is moving to the opposite side of the tank to the pump feed. How can i cure this problem? Has anyone had the same problem? Any help would be much appreciated. Thanks.

[caddyshack]

2 Caddies and this is your first post??? - Welcome!

Sounds a bit odd, I would have thought that if it were fuel starvation you should be able to get it to do it under extreme acceleration as well.

I guess you have to start at the begining and work through it...you could try jacking up the car with a large tilt to replicate the same cornering (be very careful) and see if the car will run...does the fuel filter have any in it.

If it is Fuel starvation then it must be something faulty in the tank or in the pump so I would try cleaning or replacing the pump and fuel filter and maybe drop the tank out to look and clean it.

It could be electrical, are all earths connected well and clean is anything such as steering pulling at wires etc????

[asav8tor]

I had a problem with my diesel, perhaps the gas could have the same problem.

Here is what happened:

In 1997 the motor began cutting out so I milked it into the lot of an auto parts store. Since it was diesel I could rule out spark. I reasoned it must then be either fuel or mechanical. I added injector cleaner and drove off problem free. Mechanical problem ruled out. The problem was fuel, but I did feel uneasy that the problem was solved before any cleaner had the opportunity to make it out of the tank.

The problem would reoccur from time to time. It got worse as time went by until this year (2005). Now after 8 years of fighting the engine would not run more than 5 minutes without cutting out. Over the years I tried gallons of injector cleaner, changing the fuel filter, and filling the tank. The problem would come and go and seemed to occur more often when the tank was less than half full. I assumed the injector pump was going out and I would just keep driving until it went out all the way. I read on another fourm the injector pump life could be extended with a helper electric pump. I added a Faucet electric pump between the engine compartment fuel filter and the injector pump. This type of pump makes a knocking sound when dry and then runs silent when pumping fluid. This fact allowed me to isolate the problem. On a test drive with the new electric pump silently feeding my injector pump, the engine started cutting out AND the electric pump started knocking! I wasn't getting fuel to the electric pump!

I checked everything from the pump back to the tank..... the problem was not found. It must be IN THE TANK!

I cut a approx 12" dia hole in the top of the tank. Inside a plastic cup sits at the lowest point. The fuel line connects to the cup and a fuel screen filters fuel before the supply line picks it up. The bottom of the cup is made of rubber that snaps on to the cup. The filter was completly plugged and the rubber bottom was ripped and plugging the inlet to the fuel supply line. The rubber is less than 1/8" from the inlet tube. With the screen plugged I think the suction from the inlet caused the rubber to suck up and after several years, it finally failed and ended up blocking the fuel inlet.

I threw away the rubber bottom and the filter. You can fish the filter out through the fuel sender opening with a coat hanger. And a new filter/screen can be bought. I don't want one. I rely on the engine compartment filter. So if your problem is limited to the screen you do not have to cut the tank open.

I drilled several holes in the plastic pickup elbow on the fuel pickup and placed a stainless steel mesh finger screen that just happens to have the exact outside diameter as the inside of the plastic fuel pickup. The mesh is way more coarse than the VW screen. I had this thing on hand and it worked great.

http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1130381986-88-324&browse=airframe&product=fuel-pickup

I don't know if they would sell just the finger screen part, which is all you need. I also think you could get by with no screen. Just drill some holes in the plastic elbow. I found a small round foil disk in my tank. Must have fallen off a container of injector cleaner. Without the extra holes it is possible something like that could once again block the inlet.

From the plastic cup elbow a metal tube with Oring makes its way to the side of the tank. The tube connects to the tank wall fitting with a rubber coupler. Seemed loose so I added 2 hose clamps.

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Marx: I think this is where your problem lies: The rubber coupler that connects the tube to the side of the tank. If this failed, fell apart, rubber coupler slipped causing a disconnect, the problem you describe ( cutting out in right turns ) would occur. In a right turn all the fuel would favor the left side and expose the inlet to air if the tank was less than 1/3 full (+/- depending on how fast you are going). You might be able to visually inspect this with a small light and inspection mirror (or optic fiber inspection device) lowered through the fuel sender opening, but you would need to cut the tank open to make repairs. When I was looking at this I thought it looked like such a failure was possible that is the reason I added the hose clamps.

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Then I cut a piece of sheet steel about 1" oversize the hole I had cut in the top of the tank. I then cut a hole in the middle to add the fuel sender flange I cut off the part of the tank I removed. I riveted it on with flush aircraft rivets (AN426AD3-3.5)

I then sealed the tank cover using sheet metal screws and aircraft fuel tank sealer MC236B2 developed by a chemist working for Morton Thiokol. The stuff is a 2 part mix and was developed for the Air Force B-2 Bomber program.

http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1130381986-88-324&browse=misc&product=proseal

I used this because I had it on hand.

I had an inop fuel gauge for a long time and this project gave me the opportunity to trouble shoot. It was a bad ground. I ran a new ground wire.

The engine has not coughed at all since the repair and I now have a working fuel gauge.

I wish I had figured this out years ago.

mike

[mortskeg]

Mike-
Nice write-up. I'll keep this in mind if I start having fuel issues as I'm sure there is probably some junk in that filter from the years of fuel going through. Looks like you've got some good info to share, but RV parts on the pickup? Maybe it'll make it faster. haha. :cheers:

[asav8tor]

It does go faster. For the first time ever I pegged the spedo on the 85 mph stop. ( I was going downhill with a good tailwind )

mike

[mortskeg]

( I was going downhill with a good tailwind )
Tailgate down also, right? :D :D Congrats- the big 8-5 is still mystery-promised-land for my pickup. :td

[Iowa Caddy]

Tailgate down also, right? :D :D Congrats- the big 8-5 is still mystery-promised-land for my pickup. :tdmorts -- try it with the the tailgate up. Seriously! Maybe it's not so true with our wee Caddy's, but back in the late '70's-early '80's when gas milage became really important, the CW (conventional wisdom) was to lower the tailgate for less wind resistance and better mileage. Turns out that the CW was OWT/UL (Old Wives Tale/Urban Legend). At least with full-size pu's, that is. After wind-tunnel tests, it was confirmed that there is less drag with the tailgate up. It seems that the TG up holds a bunch of still air in the bed/box, resulting in a less severe slope to the detached airflow over the cab and less drag than with the TG down. Granted, the upright TG has turbulence behind it, but not as great a drag as the more pronounced turbulence behind the cab with the tailgate down. See Kamm effect. Basically, a "streamlined" tail is more aerodynamic -- but if it's "not long enough" to keep attached flow characteristics, the penalty from turbulence at a severely chopped-off tail is less than the penalty of drag from eddies along the extra surface area. Think Rabbit GTi, or MK1 'Roc. BTW, the wee duck-tail spoilers on both of 'em is not for increased down-force, but rather to help the Kamm-effect by breaking the boundary layer attachment and modifying the wake turbulence characteristics for even less drag. :D Cheers.

edit: spelling corrections

[caddyshack]

Woah, thats some heavy tech stuff!

[asav8tor]

I added some info to my post on this thread.

********************* INFO ADDED********************************
************************************************** **************

Marx: I think this is where your problem lies: The rubber coupler that connects the tube to the side of the tank. If this failed, fell apart, rubber coupler slipped causing a disconnect, the problem you describe ( cutting out in right turns ) would occur. In a right turn all the fuel would favor the left side and expose the inlet to air if the tank was less than 1/3 full (+/- depending on how fast you are going). You might be able to visually inspect this with a small light and inspection mirror (or optic fiber inspection device) lowered through the fuel sender opening, but you would need to cut the tank open to make repairs. When I was looking at this I thought it looked like such a failure was possible that is the reason I added the hose clamps.

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************************************************** **************

[alistair]

i had the same problem with mine when i had the 1.8gti eng in it. it is a tank problem the fuel system relies on massive pressure and this drops when the tank is low round right handers, air gets sucked into the lines maybe the sport caddy had a baffelled tank or a diffrent pick up area inside it, i run the same tank now with the vr lump and dont have the same problem but the injection system works off solonoids switching so pressure is not so crucial

i guess

[mortskeg]

morts -- try it with the the tailgate up.Makes sense. Now my brain hurts. Cheers for the info- I'm off to look up the Kamm effect. :td :td

[Marx]

Many thanks for all the replies guys. These are a great help, only problem now is that the caddy wont start. The fuel pump doesnt prime so i need to check fuse and pump relay first. Does anyone know what number the fuse is in the box and which is the relay? I have no manual and its different to my other dub.

[mortskeg]

What country are you in and what year is your pickup? The fuse/relay panels are not the same on all. :)

[Marx]

Im from the UK and its a J plate (1991)

[alistair]

have you checked to see if there is a live feed to the pump?? pull off the red wire stick a test light into it and have some one turn the eng over it only becomes live when it gets a feed from the coil "i think" so the engine has to be cranking if there is a feed. its the pump thats knackerd, also you could just take a live from the battery and go stright too the pump, if the pump works you know its a fues/relay/wiring fault, do either of thees tests first then you know where to be looking for the fault