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Fuel Tank Cleaning
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TOPIC: Fuel Tank Cleaning

Fuel Tank Cleaning 4 years, 9 months ago #41926

Drained and removed the fuel tank this afternoon. Yuck! I think I know why it hardly ran. It's an '86 eta chassis. Radiatorconnection's site is down so I'll have to give them a call in the a.m.

The tank appears to be fine externally (I am tired and it was getting dark though). I guess my course of action is one of economics. If I can clean/get the tank cleaned for less coin than a replacement, I'll go that route.

My initial plan for cleaning is to see if one of the local radiator shops can tank it. Plan B would be some sort of DIY cleaning process.

Any one care to share their tank cleaning experience?

Thanks,

KB
Kevin Butler
Mobetta Autosport #612

Re:Fuel Tank Cleaning 4 years, 8 months ago #41928

  • jlevie
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A twenty year old car with a steel gas tank can have a surprising amount of
rust in the tank. That rust can and will clog the pump inlet screens and
filter and cause the high pressure pump to have a short life. While a
new tank will certainly fix that, you can clean and seal the tank for a lot
less money.

My 87 325is suffered from this. The car ran fine on the street but the first
time I took it to the track for a test & tune it was as if the car had a soft
rev limiter that decreased by 500-700rpm per lap. Some particulate matter did
come out of the tank when I drained the gas, but with the in-tank pump out I
could see a layer of crud in the bottom of the tank that was about an 1/8"
deep. On the track that stuff got stirred up, clogged the inlet screens &
filter, and starved the engine. It also ate up the internals of the high
pressure pump. Rust is a fairly abrasive material.

The first attempt at a fix was to have the tank acid dipped and install new
pumps & filter. Either they didn't leave the tank in long enough or the acid
was a bit depleted, but the result was less than satisfactory as the next time
I had the car on the track the high pressure pump started buzzing and I ran
into the same starvation issue.

After taking the tank out again and sloshing about a gallon of fuel around I
got loads of rust out of the tank. The new filter was heavily loaded and the
inlet screen of the high pressure pump was also loaded up. And the cross-over
pipe was completely plugged. This time I was determined to get all of the rust
out and follow that up with sealant to lock down anything that was left and
prevent further rusting. I used a gas tank sealer kit from Eastwood, but went
a bit further than they suggest.

The tank, having been recently acid dipped had no varnish in it. So a simple
wash with a strong TSP solution removed the remaining organics. I made up a
simple plug for the hole where the in-tank pump mounts that could easily be
removed. Think of a round disk of plywood with a bar on the bottom and a couple
of screws to snug the bar up. Drop that into the opening, rotate slightly to
engage the lock ears on the tank and tighten the screws. The remaining
openings were closed up with pieces of a freezer bag held in place with rubber
bands.

About a gallon of diluted acid in the tank was about right. That was enough to
slosh around well but not so much as too make the tank to heavy. I used an acid
mix sold for cleaning masonry that's composed of Hydrochloric and Phosphoric
acids at about double the normal dilution. Over the course of a couple of
hours I'd slosh and flip tank every fifteen minutes to wet all parts of the
tank with the solution. At the end of a couple of hours I drained the tank and
disposed of the pretty well spent acid by reacting it with limestone gravel.

To flush the tank I made up a right-angle spray nozzle with pluming fittings
and a 1/4" hose barb. That allowed the nozzle to be inserted into the tank and
a high velocity stream sprayed into all corners. This was done with the tank
at about a 30deg angle (drain plug hole down) and the fluid collected into a
bucket. When the water ran clean and no more loose junk came out I repeated
the acid treatment and flush. It took all of one Saturday and part of Sunday
to get the tank to the point that no more rust could be seen and nothing was
being flushed out of the tank.

The last steps were to use the acid etch from the Eastwood kit, flush with
acetone, and apply the sealer. Before putting the sealer in the tank I removed
the cross-over pipe and sealed those openings. And after the sealer had been
applied and before it had a chance to harden I blew out those openings and the
tubing that runs across the top of the tank with compressed air. After drying
for a couple of days the tank was reassembled and reinstalled in the car.

Once sealed the inside of the tank had a fairly uniform white coating. I did
see a few specks of matter that I wasn't able to flush from the tank, but
those were well locked in place by the sealer.

Cleaning and sealing the tank is pretty labor intensive. But at a total cost
of less than $80 it is a lot cheaper than a new tank (~$400 for this car).
Jim Levie, #38
MidSouth Spec E30 Series Director

Re:Fuel Tank Cleaning 4 years, 8 months ago #41930

  • IndyJim
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I forget the place (its in Canada), you can buy an aftermarket tank for around $250 I think.

Search on new fuel tanks, I got the number off this site. Its in New Brunswick.

If you want another option vs. cleaning.
Jim Robinson

|DTOMracing.comĀ© | - your online source for bad attitude

Re:Fuel Tank Cleaning 4 years, 8 months ago #41999

Awesome right up Jim! The most cost effective replacement tank I've found is $265, so I guess I'll be following in your footsteps.

Question: Was the amount of sealer with the kit (2 pints)enough, or did you need extra material? I suppose before I order I should decide if I need to order an extra pint or quart. Usually, my luck with application of predetermined quantities always falls short.

My local radiator shop said they may could dip the tank for me. I'll get it to them tomorrow to find out. If no go, I guess I'll be doing all the cleaning myself. Everything looked to be dried out last night. There's a lot of rust in there!
Kevin Butler
Mobetta Autosport #612

Re:Fuel Tank Cleaning 4 years, 8 months ago #42001

So in thinking ahead to the next requirement after the tank issue is resolved, fuel pressure comes up.

My chassis has the 2 pump system. I haven't looked at prices yet, but if I can convert my 2 pump system to a single pump system, all the better. Anybody converted the pumps on the old style tank?
Kevin Butler
Mobetta Autosport #612
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Re:Fuel Tank Cleaning 4 years, 8 months ago #42002

Hey Jim,

Will a '88 tank fit in a '86 car?
Kevin Butler
Mobetta Autosport #612

Re:Fuel Tank Cleaning 4 years, 8 months ago #42004

Ok, I finally found the $175 radiators on ebay - theradiatorconnection. I'll easily spend $80-$100 on just materials and service alone - not to mention my time and the mess. So, I'm down for a new radiator.

Ok, that being said, my current chassis is a '86 eta w/14.5 gallon tank. I'd like to upgrade to the 16.6 gallon '88 tank. Has any body done such a thing and what all additional parts did it entail?

Additionally, I really want to ditch the old dual series pump setup and go with a single pump system. Anybody been there, done that?

TIA

KB
Kevin Butler
Mobetta Autosport #612

Re:Fuel Tank Cleaning 4 years, 8 months ago #42015

  • Ranger
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Jim, that was a great post. I'm going to put it on my website in the DIY's section. With due credit of course.

rroadster. The Grassroots motorsports guys fought this battle with their E30 last year. They wrote a series of stories, one of which talked about buying the wrong fuel tank. I'll look for the article tonight, but I'd give them a call and see what they learned from that.

I don't recall ever reading a post here about someone trying to convert from old to new tanks. It just became legal this year.
Your opinion counts.

Re:Fuel Tank Cleaning 4 years, 8 months ago #42016

Thanks Ranger,

Is this the article you speak of?

grassrootsmotorsports.com/project-cars/1989-bmw-325is/fuel-tank-frenzy/

This says GRM tried to put a smaller tank in a later model car - with no success.

That makes me nervous about trying to fit the larger tank in my earlier car. Too bad - I was hoping for a 12 hr Enduro killa!

I still am going to persue a single high pressure pump in the tank and dump the external pump. The internal pump I removed was someone's attempt to rig a non OEM pump in the tank. The pump leads came out of the pump while I was trying to wiggle the fat S.O.B. out of the tank hole.
Kevin Butler
Mobetta Autosport #612

Re:Fuel Tank Cleaning 4 years, 8 months ago #42018

  • Ranger
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rrroadster wrote:
Thanks Ranger,

Is this the article you speak of?

grassrootsmotorsports.com/project-cars/1989-bmw-325is/fuel-tank-frenzy/

This says GRM tried to put a smaller tank in a later model car - with no success.

That makes me nervous about trying to fit the larger tank in my earlier car. Too bad - I was hoping for a 12 hr Enduro killa!

I still am going to persue a single high pressure pump in the tank and dump the external pump. The internal pump I removed was someone's attempt to rig a non OEM pump in the tank. The pump leads came out of the pump while I was trying to wiggle the fat S.O.B. out of the tank hole.


GRM's situation apparently wasn't exactly like yours, but they still might be able to offer some insights. They had a late model car and bought an early model tank. So you know that they held their single late model pump in their hand and looked hard at their early model tank and thought to themselves...."can we make this work, or do we need to send the early model tank back."

And if they did some thinking along those lines, then they're likely to have some insights into your situation which is pretty much the opposite. The guy to talk to might be Scott Lear.

That's a little weak, but it's not like you're being inundated with other advice.
Your opinion counts.
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