MilkStout

iTrader: (1)

took the FB to the strip, ran 20s both times....seems in 3rd gear at about 4k the car stops accelerating and the rear starts to bog back and forth....sounds like its not getting fuel. not sure but i couldnt go faster than like 60.... =[ i let off and there was a giant *** backfire and as soon as i went on the gas it was fine for about 2 secs before acting up again. if im not full throttle it doesnt do this but then of course thats no bueno when your racing.

any ideas? ill admit im not the most knowledgeable person but im learning...i was told the fuel pumps are crappy and can cause this.

Cookboy

iTrader: (10)

Fuel pickup in tank is clogged with rust. I betcha.

MilkStout

iTrader: (1)

hmmmm interesting.

t_g_farrell

iTrader: (1)

Fuel system issue. Check the filter. Check the flow and pressure at the carb. Like Cookboy says
it could be crap in the tank as well. You'll see it in the filter if it is.

Cookboy

iTrader: (10)

My 85 showed same symptoms. I thought I could clean the tank by replacing fuel filet every couple weeks (they filled with crap). Finally dropped tank, actually an easy job, and was amazed it would even run at all. The pickup had no visible way for fuel to be picked up.

Bought a couple bags aquarium gravel, shook them around, dumped. Probably a quart of rust/crap mixed in w gravel. Then bought several jugs of water based deruster, left in tank for several days at different attitudes to get rest of rust. New pickup sock, and no issues since.

MilkStout

iTrader: (1)

guess ill be cleaning the tank =] couldnt hurt either way in a 30+ yo car.

Cookboy

iTrader: (10)

When you do, replace the lines and clamps, sand and repaint the tank, at least the top if its otherwise well undercoated.

Report back with what you find in there.

MIKE-P-28

iTrader: (1)

I have been fighting a gas tank for several weeks. Lol I have it out and wanted to go ahead and completely clean it up before I completely put the car back together. I've tried several things. Thing I found that works the best for cleaning the tank is : strip the tank remove sending unit, hoses etc. : first thing mean green or purple power and a pressure washer. Stick that sucker in there and spray. Rinse rinse rinse keep rinsing. Drain. Make any welding repairs now. If you rinse the CRAP out of the tank you can weld on it. Just be smart. If it still smells like gas go BACK to step 1!!

Then use acetone. Buy a gallon. Use about a quart at a time. It will remove any crud that's still stuck in there and it will also clean up the left over soap that's still in there . You can then use a good gas tank etc it will attach itself to any rust in the tank and convert it to zinc oxide. Then use some sort of gas tank sealer. POR 15 or Etc. I used the one from TP tools (Bill Hirsch etc and sealer). Tank looks pretty good inside now. Just hope it holds up. Time to spray the outside with a can of bed liner spray. I try not to use undercoating that stuff sucks in my opinion. Too sensitive to chemicals and breaks down if you drop gas on it.

As a side note Muriatic acid kicks *** for cleaning a tank. It'll eat EVERYTHING in that tank quick as hell but it also eats the galvanized coating and starts to rust almost immediately after you drain it. You have to work REALLY FAST!

mazda6guy

iTrader: (1)

Cookboy where did you purchase the new fuel pick up sock?

Cookboy

iTrader: (10)

I went to advance auto and picked thru what they had til I found one that fit the tube.

mazda6guy

iTrader: (1)

OK Thanks because I was having a hard time finding one through other places on the internet. I am having the same fuel issues as in this thread and will be dropping the tank today after work. I think mine might be rust related in the tank but I have never dropped the tank to clean it the whole 10 years of ownership so it should not hurt it. Did a track day last weekend and had major fuel issues all day. Never ever use a cheapo fuel filter. I cut it open and it was a very thick piece of cardboard as the filter element. Will be ordering a couple of Wix fuel filters today for it.

74RX4

iTrader: (10)

Marine clean that POR-15 sells works great.
MARINE CLEAN - WATER BASED DEGREASER-POR-15 Inc.

Here's how I do it. No rocks, chain or harsh chemicals.

Seal the openings with duct tape except the large hole for the pickup and sending unit. Add a cup of Marine Clean to the tank. Bring a big (2 gals or so) pot of water to a boil and pour it into the tank. Seal the last hole. Swish it around, turn the tank upside down and sideways until you are sure the entire inside has been covered. Turn it right side up. Let it soak over night. Remove the tape from the large hole and dump it (in a safe way). Repeat if needed (I've never had to). Remove the tape on the filler tube hole and stick a garden hose in it. Overflow the tank with water for several minutes. Remove the hose and drain the water. Position the tank so the large hole is the lowest point and let as much water as possible drain out. Put a wet vac hose in the large hole and connect it to the blower side of the wet vac. Leave it on for 24 hours to be sure all the water is evaporated. You will be amazed at how clean and shiny the inside of the tank is.

The link below is pictures of the first GSLSE tank I did back in the 90s. I used the complete gas tank kit from Por-15. I've done 5 more tanks since then. Now I know the rust converter and sealant (silver coating) is not needed unless the tank has rusted through.
83 GSL and 84 GSL-SE Fuel Tanks

Cookboy

iTrader: (10)

Marine clean looks great! Next time...

flight_of_pain

Under the banjo bolts on top of the Nikki are two tiny screens that filter the fuel into the float bowls. If these screens collapse or get clogged they don't allow enough fuel flow to run the engine at WOT once the float bowls drain.

I fought with a similar issue years ago, car would run fine around town or in a bit of spirited driving, but would bog out and do all sorts of nasty things at the top of 3rd. I cleaned the tank, replaced filters, blew out lines, ect, ect. I wasn't until I had just about given up that I pulled the fuel distribution pipe off the carb and saw that those screens had collapsed and I realized the problem.

Isaac

MilkStout

iTrader: (1)

im going to check the whole fuel system. but i dont think cleaning a 30yo gas tank is a bad idea =] so ill just do that as well.

74RX4

iTrader: (10)

You can remove the left rear wheel and gain access to the removable plate and fuel lines on top of the tank. It is held in place with 8 or so small phillips screws. A short screwdriver can be used to remove them. Be careful not to strip the heads. With the plate removed you can look into the tank with a flashlight to see how bad it is. Make sure the tank is close to empty.

MilkStout

iTrader: (1)

so i changed my fuel filter and no more fuel cuts!!!

i canWOT in every gear all the way to or past redline.

i can also go faster than 85 (the speedo limit)

wayy faster =]

so it was just a simple fuel filter. that took 5 minutes to change.