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What fuel pump is used in '80 Avanti?


WayneC
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I have a weird issue with my 1980 Avanti.

My driveway is on a fairly steep incline. If I leave my '80 parked uphill on the driveway for any extended time, it refuses to start, cranks until the battery runs down but no gas is getting pumped to the carburetor (disconnected the line at the carb and nothing comes out while cranking).The gas tank is more than half-full.

If I get it down to the street where it sits level, and wait for awhile, it starts fine after cranking a bit, and runs strong thereafter.

I've checked and changed the inline filter.

I am thinking maybe a bad fuel pump or blocked feed line to the pump, but neither really explains why it starts and runs fine on level ground.

Any other ideas?

Anybody know the application for a fuel pump in a 1980 Avanti? I'd like to have parts in hand before tearing into it (actually, I intend to have it done and would like to be able to bring the parts along with me to the shop). Tried to take some pics with the car on the ground, but couldn't get any good shots of how the lines connect to the pump, the pump is really crammed between the front frame crossmember and the engine.

I thought perhaps Malibu, but the Malibu pump doesn't look right to me.

I did find a C10 pickup pump for a 305CI V8 that does have 3 tubes plus the hex fitting:

http://tinyurl.com/hk3hubr

Wayne

Edited by WayneC
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Try an Edelbrock, Holley or Summit racing fuel pump that's clockable so the fittings can be aligned with the lines. There's a number of small block Chebbie fuel pumps out there depending on actual application. They all might fit the block but the fittings can be different.

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Also check for a pinhole leak in the fuel line or rubber flex hose at the tank....These can be tricky!...

Years ago, I drove a '76 Impala that had the same symptoms, and the problem turned out to be a cracked fuel rubber hose.

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The hose connecting the gas tank to the fuel line tube was recently replaced (after the issue started). I've not noticed any fuel leaks.

Here is a larger version of the pic I posted initially (it may take a few seconds to load):

http://tinyurl.com/joqjksl

It looks as though there are 2 rubber hoses going to the pump, in addition to the steel line to the carb.

I need to get more/better pics, it's maddening to not quite be able to see the fuel pump, but here is an editor-enhanced and annotated photo taken from in front of the right upper A-arm pivot,

perhaps this pic will jog someone's memory...

http://tinyurl.com/glfvuhr

I labeled one item (near top left) as "hex fitting", I assume at the end of the pump-to-carb steel tube, but I am not sure of that.

IIRC. there is a "T" in the steel fuel line (that runs along the frame) at about the center of the car, with a second steel tube running forward from the "T"... never really understood the reason for that (re-circulation of fuel through the pump?)... could that steel line to the upper left on the photo (annotated by "???") be routed from that "T"? Or is that tube actually the fuel line and the tube I labeled as "fuel line from tank" is the extra tube?

Either way, does that mean the fuel pump needs 3 fittings?

I did find a C10 pickup pump for a 305CI V8 that does have 2 tubes plus the hex fitting:

http://tinyurl.com/hk3hubr

Edited by WayneC
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You could use one from a 1980 chev blazer, full size 305/350 V/8, that is what I have on my !985. The third line it is in the center is a return to the tank,it is necessary with the alcohol laced fuel being sold today and because as we all know the Avanti is very warm under the hood read vapor lock. Lou Cote

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Assuming that your car still has the origional fuel pump don't you think it's about time to replace it? The ethanol based fuels are hard on all rubber products: hoses fuel pump diaphrams etc..The " T" fitting on the frame about the middle of the door is the main pump feed ,that has a plug in it to drain the fuel tank,if you need to. When you get to the point of replacing the pump, pack the pump cavity with clean chassis grease as todays motors don't put much oil to lube the pump. Lou Cote

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Looks like the Blazer has the hose connections headed in the wrong direction for my car unless the my steel fuel lines were to be re-routed and cut in length, but you've confirmed that there are 3 fuel ports on the pump, 1 in and 2 out (?), so that's a step in the right direction. I wonder why the extra line only returns a few feet and joins the main fuel supply line from the tank... don't really understand how that loop prevents vapor lock, or for that matter, how a simple "one line in, one line out" fuel pump manages to maintain pressure no matter the flow rate to the carburetor.

My '71 Avanti has the same style fuel line with the T-junction along the outer frame rail although I think the return line rose up into the engine compartment (never went to the fuel pump) and was simply capped off ... I need to check that.

I had always assumed that the extra few feet of steel fuel tubing was originally needed by supercharged Stude Avanti's (not sure why) and the same tubing was simply used as is from the parts stash purchased by Newman & Altman when the Avanti-II was built. Must be some info somewhere about that second fuel tube. My guess is that its purpose is to reduce pump cavitation by giving excess fuel a place to go rather than churning within the pump itself; but it would make more sense to me if it went all the way back to the tank instead of just back a few feet before rejoining the main fuel line.

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Thanks for your comments, Lou. The car is original and relatively low mileage at 50k, runs great but certainly showing lots of age (its my '71 that is shown in my forum avatar).

Maybe my previous comment about my '71 was wrong and the "extra" fuel tube does go all the way back to the tank... in fact, I removed the fuel tank from the car some years back and took photos which I just reviewed, and there appears to be a rubber hose coming through the floor on the left side just in front of the tank and going up and Tee'ing into a "Z" shaped metal tubing pipe criss-crossing the length of the tank, a few inches above the tank... I don't recall where the other end of the hose goes, it may just be open to the atmosphere.

I also seem to recall that the '80 has a smog emissions vapor cannister in the engine compartment, which may be where that same tube might terminate on the '80.

Time for me to stop talking and go look (maybe tomorrow, but I have an XJS with big problems I need to tend to). Old age is a terrible thing.

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That is the correct pump, it's important that it has a shallow lower chamber, as there is a type with a deep chamber which will not clear the Avanti's frame.

If there's an AUTO ZONE store near you, the part number for the pump you want is.......M-6626

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The charcoal cannister does not connect to the fuel pump, the cannister is used to collect fuel vapors from the tank and is connected to a hose that is connected to the carb,vacuum pulls fumes in. This is with a non vented gas cap.. The AC pump is identical to the one that I bought from Dan Booth. Lou Cote

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The charcoal cannister does not connect to the fuel pump, the cannister is used to collect fuel vapors from the tank and is connected to a hose that is connected to the carb,vacuum pulls fumes in. This is with a non vented gas cap.. The AC pump is identical to the one that I bought from Dan Booth. Lou Cote

I was replying to his photo of hoses with question marks. Yes, there is only fuel, and not fumes connected to a fuel pump. (unless you vapor lock)!!!

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RQB3263 BILL GREGG 81/305....I just did this on my 81....and found the receipt for the pump...CAR QUEST #FP 41216....and is also listed for a C-10 5 liter/305.....Its a good idea to change the pump...However I doubt it going to fix your problem....and for sure do-not back up your driveway...your liable to get fuel gravity feeding back thru the carb and possible hyd. lock ....this could bend and break all kinds of things....or major back fire and engine fire.....Find a level spot to park your car ....good luck ....BILL RQB3263

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....and for sure do-not back up your driveway...your liable to get fuel gravity feeding back thru the carb and possible hyd. lock ....this could bend and break all kinds of things....or major back fire and engine fire.....Find a level spot to park your car ....good luck ....BILL RQB3263

Unfortunately the only level spot is the street. I would not park facing down the hill, and I doubt it's possible anyway, because the wheels would just spin trying to back up into the driveway.

Possibly the fuel pump or a pinhole in a fuel line that doesn't leak fuel but lets air into the fuel pump.

Forgot to mention its been parked on the driveway for years, rarely driven. But it always started just fine until recently. I have another car parked on an even steeper grade behind the Avanti, but starting it has not been an issue.

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Edited by WayneC
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