Need some advice or suggestions on my fuel system dilemma. While overhauling the brake system (new lines, hoses, calipers, …) on my ’66 Coupe I also replaced the two fuel hoses. I drained the fuel tank at the fuel pump hose location. The flow out of the tank was good as expected and all the fuel was removed except for a half gallon or so that remained in the forward area of the tank. After completing the brake work I refilled the tank with about 8 gallons of new gas. The engine wouldn’t start and in trouble shooting I was dismayed to find that not a drop of fuel was reaching the inlet of the fuel pump. Further inspection show that some fuel is making it to the tank outlet hose but given the low rate of weeping that occurred when the clamp was removed and the hose slid back towards the bead a severe restriction was probably occurring upstream in the tank. A limited inspection of the tank internal surfaces (including the upper surfaces where I would assume it would be more likely) indicated no visible corrosion (this is an original Southern California car with very little rust), although there is some rust colored debris laying in the forward sump section of the tank. Seems like I have a clogged strainer on the fuel sending unit that occurred as a result of draining the tank. Possibilities are: 1) large contamination due to something like a small plastic bag, 2) accumulation of particles (rust, dirt, etc.) or 3) formation of “gas varnish” on the strainer that accumulated over the several month period in which the tank was drained in combination with particulates.

I thinking it’s 2), the particles, and I am somewhat resigned to pulling the sending unit if not the entire tank. If I go that route I will of course verify the metal fuel line along the frame is clear of any blockage before removing the sending unit. Any other ideas or suggestions? Assume it could be varnish and give it some time to dissolve? Any tips on removing the sending unit?

 

Check the hose that you installed at the tank to make sure that it is not kinked. It is easy to do. Also, initially the fuel will not flow because there is a hump in the internal line. You must get some fuel in the line for it to syphon.

 

I did check for kinks and found none. When I installed the rear hose I was sensitive to the possibility of kinking, especially at the clamp to the frame. I hadn't thought of having to siphon to get the fuel over the hump of the sending unit, outside hose and down the metal tube along the frame. I assumed gravity would be enough. I'll give it a try. Sure beats pulling the sending unit. Thanks for the suggestion.

 

I would think that during your draining, sediments filled up the screen and may have dried or bonded together in some way over time.

What you could do if this were the case is to blow some compressed air into the tank via the rubber connection hose. This may dislodge the debris. If this is the case, I would fill the tank with 5 gallons of gas, blow the sediment free and then pump the gas out with an electric pump with a filter on the suction end. The sediment may be suspended temporarily in the fuel and then the fuel removed with the pump, and the sediment filtered out with the pump filter. Use the gas over again if necessary. With the tank empty you could use a rag and attempt to wipe the bottom of the tank as well.


Mark

 

i had a fuel starvation problem on my 66 that i resolved by pulling the tank, draining it and removing the sending unit and replacing the strainer. it was not a big job use a brass punch on the sending unit retainer cam to ensure you don't damage it. replace the strainer, mine had turned to varnish
i also had a section of fuel line that was 5/16 rather than 3/8 which contibuted to the problem, and i replaced with good quality fuel line so it would never collapse on me. i cleaned out the fuel tank fully before i installed it and the difference was amazing
start with the tank and ensure you have no issue there. if the strainer has never been replaced i'll bet this is a big part of your problem along with the junk that may be at the bottom of your tank

 

I appreciate everyone's suggestions. My plan of attack is: 1) Try to initiate flow with a hand vacuum pump at the fuel pump hose. Achieving good flow would validate wombvette's point that the siphoning effect may not be in place yet (the fuel level may be just below the high point of the sending unit pick-up tube, trapping a small pocket of air) and would indicte that there is no blockage of the strainer. 2) Failing step one, pull the sending unit and replace the strainer as Hotrod66 suggests. After looking at the Assembly Manual it looks like a fairly simple task. The only tricky part is what to do with 8 gallons of questionable gas!

I will probably do the job this weekend and will post back the results so someone else may benefit from what I learned.

 

check the (flexible)fuel line between the main stainless line and the fuel pump, I have had them look good and not even leak but were aged or perforated just enough to suck air and not pull fuel into the fuel pump

 

After looking at some pictures of the sending unit, it dawned on me that if the pump was bad and the fuel level in the tank was below the high point in the internal pickup line no flow would occur (assuming the strainer wasn’t clogged). To test this I first measured the fuel depth at the pickup point using a wooden dowel. It measured at 5.5”. I estimated the height of the pickup tube high point to be approximately 7.5” by scaling to the external flange in a catalog image. I then disconnected and clamped off the rubber fuel line at the pump and added 4.5 more gallons of gas to the tank. Crawled under added a clear tube to the now disconnected rubber tube and placed it in a container. I then released the clamp and within seconds I had good continuous flow from the tank.

Having solved the first mystery I knew the pump was going to be bad. I clamped off the hose once again, connected it to the pump and released the clamp. Within a couple of seconds I started to get drips from the weep/vent holes located above the diaphragm. I clamped off the line again, disconnected it from the pump and plugged it as a backup.

I then removed the pump, which I’m thinking may have been a mistake. There wasn’t anything in the 1966 Chassis Service Manual saying to get a certain cam position but I got to think that there is an “easier” position. #1 cylinder TDC? Anyways the pushrod is difficult to lift. I’m looking for recommendations on how best to install a new pump on a 427.

Remove the pipe plug and take the pushrod out through the hole, then set the engine position?

Can I bump the engine to the new position without taking the pushrod out?

What the best way to hold the pushrod up while inserting the pump lever arm? Something up through the pipe hole?

 

Quote
"What the best way to hold the pushrod up while inserting the pump lever arm? Something up through the pipe hole?"

I use my remote starter to bump the motor over. I put my finger up into the pump boss and feel when the rod is at BDC. I then sild the rod out a an inch or so and put a dab of grease on the shaft and push it back up. The grease holds it in place. If the motor is warm at all, the grease will not hold.

I think there may be a location to run a bolt up lock the rod in place. In any event, I think pump install goes alot easier if the rod is at BDC.

Mark

 

aahhhh, a man in search of the "tricks" for replacing the fuel pump.

I STRONGLY suggest an archive search, in any event there are a few good methods, the one I used (learned about from the archives and from pals here) involved removing the bolt on the front of the block just above the fuel pump area and inserting a longer bolt in there, which holds the lever arm up. Also helps to have the cam in a non-engaged position, so you are not having to struggle to compress the fuel pump diaphram while you are tightening the two bolts down. One other GREAT tip from the archives: take the right front wheel off first - you can atually see what is going on better, AND you can use a couple of ratchet wrench drive extenders and have direct access to those two bolts.

still, with all of those happy tricks I have memories of laying on a cold conrete floor in my unheated garage in the winter, fuel dripping on my face, really tight access in that area - another amazing opportunity to swear like a sailor while "enjoying" ths hobby of ours.

 

Took your advice and did an archive search. Found many postings for small blocks but I'm dealing with a big block. I eventually found a couple of good ones in the C3 section. My plan is to bump the engine to a position that allows the pushrod to be lifted as high as possible towards the cam, apply grease to hold the pushrod in position as ghostrider suggested, then install the pump. If that fails I will remove the BB only pipe plug that is located below the pump interface and directly inline with the pushrod, then use a thin device (hacksaw blade was one suggestion) to hold the rod up as the pump is installed.

Looks rather straight forward after reading the trials of others. Another nice aspect of living in San Diego is that no matter how smooth or difficult it goes I won't have the memory of laying on cold concrete in an unheated garage! Thanks for the support.