1973 Mach 1 351w Rough idle Please help

[snellet]

Hi everyone!!! I'm new here and just learning the basics of this site so bare with me please. I just bought my first Mach1 after 12 years of dreaming. This would make my total mustangs owned at 11. My 1973 Mach1 has a 351w, not original, and has been in a barn for the last 3 years. It still started but I had to keep the choke on and it ran rough. I first went ahead and ran it completely out of gas. I rebuilt the carb (1405 Edelbrock manual choke), replaced the fuel filter, and oil, and added 5 gallons of fresh gas 89oct. It ran great in the driveway (didn't have to keep the choke on) and idled smooth, but after driving it about 5 miles it stalled at a stop sign and it is idling just as rough as it was initially. I have to keep the choke on to keep it running. Very confused!! Any help would be greatly appreciated. Love the site Btw, a little tricky to get used to though.

[Steven Harris]

It sounds like it is still starving for fuel. Maybe one of your lines is still somewhat varnish closed or perhaps your mechanical fuel pump has gotten weak.

[snellet]

Thanks for the ideas Steven, I thought about replacing the fuel pump, but after it ran and idled so nice initially (after I rebuilt the carb) I figured it must be something else. Do you think if I took the fuel cap off that maybe I could clean the line out at the fuel pump with a air compressor?

[Steven Harris]

Have you tried to run some type of fuel cleaner through it? That may be all it takes. If it ran good for a while then I find it hard to think that it would be varnish (although once the varnish is wet, it would swell). The diaphragm in the pump however could go bad after drying out and then being hit with new fuel.

How about the fuel filter? Kind of sounds like you sucked up some debris.

[ohiomustang]

Get and install a change-able fuel filter
I don't trust the glass filters to leave one in permanently but would use it in this case to see what is collected.

Usually it is rust in the gas tank or lines from sitting and condensation.

They run good until the fuel sloshes around in the tank and collects the rust

Should be a filter / sock on the sending unit but the deteriorate and fall apart.

Don

Nice car, if you find the rust is in the tank I would
Blow out the lines
Replace that tank and sending unit

[snellet]

Thank You so much Steve Harris and Ohio Mustang for all of your help! I took the filter off and blew it and the lines out with the air compressor and now it is running great again! It must be debris in the tank. Next question I guess would be (sorry, you knew that was coming!), is there a way to clean the tank out myself or should it just be replaced? If it needs replaced how much would it cost to have one shipped to Freeland Mi. at Ohio Mustang?

[ohiomustang]

Usually if it is that rusty, it might start leaking next


You can change the tank, sending unit and all seals for 210.00
That will be one area you won't have to think about anymore

I also have an inmorted tank and plastic sending unit, they are cheaper

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Item #F32A
71-73 FUEL TANK
AMERICAN DESIGNERS reproduction gas tank. 20 gallon tank with out drain. Made in Canada. Price: $134.95


Item #1054
71-73 GAS TANK BOLT KIT
Price: $3.00


Item #F-992
71-73 GAS TANK FILLER NECK SEAL FASTENER KIT
4 piece screw kit. Price: $3.00


Item #D1ZZ-9008
71-73 TRUNK FLOOR TO FILLER PIPE SEAL
Trunk floor to fuel tank filler pipe seal. Price: $21.95


Item #F4ZZ-9072
81-97 GAS TANK TO FILLER PIPE SEAL
Price: $19.95


Item #GT20-71S
71-73 FUEL SENDING UNIT WITH BRASS FLOAT
Includes metal lock ring and O ring gasket. Replacement for Ford part #D1ZZ-9275C. Reproduction. Price: $32.95

[Steven Harris]

Don's the man for replacing your tank. He is both knowledgeable, fair and honest. http://www.ohiomustang.com/store/order_p...itemid=295 It looks like the price is $134.95 plus an over sized shipping charge of $38.00 if I read his catalog correctly.

Can it be cleaned, yes. Is it worth it for $134.95 and the peace of mind? My son and I cleaned his Maverick tank and repaired it because there are no reproduction units available. We have had no issues with either the repair or the cleaning but a few hours of manual labor is involved.

To clean one you first drop the tank and then pull the sending unit. Empty all of the old gas and wash it out with some water and some soap. Take a couple of handfuls of gravel (yes regular gravel) and shake it around in the tank with the soap and water. Dump it out, wash it out and repeat if necessary until all rust and scale has been removed. Be sure that the tank is completely clean and reinstall.

To be sure buying a new tank is the better option. This is a trick we used in Africa when no option was available.

Anyway - it looks like Don hopped right on to your question before I posted my answer.

[Masterblaster7212]

I just went through this scenario with my sons 67 coup mustang.

The old car had been sitting for 15 years and had rust in the tank.

I installed an extra glass fuel filter before the carb fuel filter in line, and I could then see the contamination in the lines and how much was physically getting through.
If your really tight on cash you could use the POR-15 gas tank system to clean the tank and coat it with a sealer.
I did that on my fathers 71 Jaguar (E-type w V-12)...it worked great.

Whats cool about those glass filters is that I can periodically take the screened washable filter off, clean it off, reinstall it and go again for another month or two before I do it again.

I am buying time before I have to make that big fuel tank purchase.

[snellet]

Again, thank you both for all of your support. I think my next move will be pulling the tank and inspecting it to see if it is salvageable. Thanks for the great tips on cleaning the tank. If it's not salvageable then I will definetly buy one from Ohio mustang. I will keep you both posted on my progress.