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When I started my 1702 a couple of days ago, I ran an external electric pump to get the gas to the carburetors as fast as possible. Since then I have cleaned out the gas tank and gas line and hooked everything back up. I had not removed the fuel pump up to that time. I tried starting the car with the fuel pump but the pump was not pumping. I removed the fuel pump and when operated by hand it works well. I am thinking that it is not coming in contact correctly with the cam shaft. There is a thick spacer between the pump and the block. I tried mounting it without the spacer to see if the spacer was there to take up for wear but got the same results. I have put everything back to the way I got it. The actuating arm of the pump is very long. I am wondering if there is a trick to the way it is inserted into the block to make sure it ends up on the correct side of the cam or some other thing I may be doing wrong. Does anyone have experience with this? Thank you in advance for any help you can provide.
Steve
Call John Cislak. He will be in the shop tomorrow. The arm runs off a horizontal pin. It need the spacer.Ed.
Hi Steve, when you put the arm through the mounting hole in the block, you can feel the cam lobe on the csmshaft,
You are correct, it is easy to either miss the cam lobe entirely, in which case the pump arm rides on the camshaft round section, and there is no pumping action.
OR, when you feel the cam with the pump arm, and try to keep the arm on the cam while starting to thread the bolts into the block, while juggling the two gaskets, and the spacer. And there is no room for an extra hand to hold everything in place while getting the mounting bolts started in their holes.
The result, is the arm slides off the side of the cam and you have no pumping action.
You can feel the pump arm on the cam, and you can feel the pump action in the pump.
There are a few tricks that can help, first, get longer pump bolts, to be used only to line up the pump, gaskets and spacer, then once one long bolt is installed, you can confirm the pump arm is still on the cam. Install one normal mounting bolt, then remove the long temporary bolt and install the correct length bolt.
I have found that the pump may pump on the bench or in your hand, but not on the car.
I had replaced the diaphragm in my pump, but it still did not pump enough to run my engine over idle speed. It just did not put out enough fuel volume.
I removed the pump top, while the pump was still mounted on the engine. When I cranked the engine over with the starter, i found that the pump diaphragm was only being pulled down level with the gasket surface of the pump, or said another way, the diaphragm was only pulled down till it was flat. It needs to be pulled down untill it is below the mounting surface, by about 3/16″ . The up movement of the diaphragm is limited by the pump design.
I had to make a new, shorter diaphragm center peg, or stake. with a pin about 3/16: shorter, the pump works fine and pumps plenty of fuel.
There are several other possible issues with the fuel system, Any air leak will allow the pump to pull air instead of fuel, the venting of the fuel tank may be plugged.
Did you replace the diaphragm in the fuel pump? If not, don’t run the pump until you have a new diaphragm that is ethanol/modern gasoline compatible, otherwise the ethanol will turn the diaphragm into a soft gooey gummy mess, and fuel will leak through into the crankcase, diluting the lubricating oil resulting in engine damage..
Email if you have questions.
Greg Long
Here is the diaphragm with the lever on the low part of the cam lobe, This is the maximum upward travel of the pump mechanism.
The previous photo shows the diaphragm at it’s maximum downward travel, when I made a new shorter center shaft or stake for the pump, the diaphragm would be pulled as far below flat or level as it rises above level. The result is about 3/8″ or 7/16″” of travel.
Greg L”
I purchased a kit from Egge to rebuild the fuel pump in my 1935 Model 845. When I tested the pump on the bench there was no pressure. Looking in an old MoToRs manual, it indicated that the two springs had to be replaced in their original position. I replaced the springs with the original springs in their original position. Bench check showed good pressure. This is somewhat perplexing as both springs appear to be the same.
I might add that a weak spring can be a problem. A common misconception is that the camshaft-driven arm does the pumping; not true. The arm pushes the diaphragm against the spring pressure and the rebounding spring does the actual pumping.
Right above your fuel pump mounting, you’ll see a pipe plug. Remove it and if possible look (or feel) for a protruding nipple. Your fuel pump arm MUST ride on this nipple. As you install your “REBUILT” fuel pump you can observe its’ proper alinement. Greg is 100 per cent correct–put in a new ethanol friendly diaphragm–your old one may last a short time; but, may cause you some real nightmares. If that nipple or pin is missing it, more than likely can be found in your oil pan.
As you can now understand, the eight fuel pump mounts on a cam lobe–the V-12 rides on that nipple/pin, that rides on the cam.
Good Luck
After reading Bob’s message above I ran out to the barn and looked at the old V12 crankcase I have.. I didn’t realize that the fuel pump does not run off the camshaft !! I ASSUMED it did.. LOL..
OK, the pump arm rides on a small lifter, only about 3/8″ or maybe 1/2″ diameter, this lifter is horizontal. the cam or eccentric is on the oil pump shaft, which is run off a gear on the back end of the cam. this gear runs the oil pump and the distributor.
The photo below shows the outside of the block with the mounting pad for the pump, and above it, is the pipe plug Bob mentioned. Once the plug is removed you should be able to see or feel the pin or lifter that the pump lever rides on.
Greg L
Here is a photo if the inside of the V12, The cam and gear is on the left, on the right is the crankcase wall with the rectangular hole for the fuel pump arm on the lower right. The hole for the pipe plug is upper right.
Between the pipe plug and the cam gear is the bump or boss in the block for the lifter or pin that rides on the oil pump shaft’s cam, and pushes on the fuel pump arm.
Greg
Greg,
I don’t see the rectangular hole for the pump in the second photo so I cannot visualize the orientation of the photo. Do you have another view of this? I can’t see where the path of the long fuel pump arm would go. Thank you for all of the help so far. It is truly appreciated.
Steve
Hi Steve, this engine is sitting on it’s bell housing, so the cam and crankshaft if installed are standing vertically.
In the second photo, there is a diagonal brace from the main bearing to the side of the engine case, just ahead or above the brightly lit diagonal brace is a shadow that is the opening for the pump arm in the block.
I might have a better photo to post, but I will dig up a pump and poke the arm through the hole in the crankcase, so it will be easier to see the orientation.
What I would do on your car, is to remove that plug in the case just about 5″ above the pump mount pad. Then you can put a finger through the hole and feel the pump arm and the pin or lifter it should be riding on.
Greg Long
“
Greg,
Yes, I think I see it now. Thank you for the clarification. I will be working on it tomorrow and will take out the plug to see that the arm is positioned correctly.
Steve
Here ya go. I took a fuel pump out to the barn, put it in the pump location so the arm would stick through the hole in the crankcase. I put a bolt on the boss for the lifter. I wanted to put the bolt through the hole in the boss, but it is plugged with hardened old grease.
This is not the correct pump or lever for a V12, your pump’s lever is like a long skinny ‘S’ curve or something like that. I used this one because it had the longest arm I could find.
But I think you can now see where and how it would work with the correct pump.
Did you remove the pipe plug and look or feel through the hole ?? you can see the recess in the crankcase to the right of the bolt sitting on the boss.
Greg Long
Greg,
It all makes sense now. I will be going over to the garage tomorrow (Monday) to work on the car and I will remove the plug and see if everything lines up as I remount the pump. Thank you.
Steve
I finally solved the non-working fuel pump problem. The saddle on the arm that pushes down the lever attached to the diaphragm was badly worn. The play in the arm before engaging the lever was about equal to the travel of the arm when moved by the pin in the engine. I brazed some material into the saddle and the dressed it with a file to add about .050 to the arm. This took up the slack and now the fuel pump works well. Thank you to all, especially Greg, for your help.
Steve
Steve, you are more than welcome, I’m glad you sorted it out.
Did you drop the oil pan on the engine, and clean the sump, clean the screen on the oil pick-up ‘floato’ ? Also, make sure the ‘floato’ oil pick-up pivots up and down freely so it will reliably and consistently draw oil from the sump.
Is the original oil filter system still on the car? Have you installed a replacement oil filter, or installed one of the kits to replace the internal parts of the old oil filter with a replaceable spin-on modern oil filter ??
I highly recommend that you do not drive the car much at all untill the lubrication system is inspected and cleaned.. It’s incredibly expensive to rebuild a v12 engine, so I’d do everything I can to make sure there is no damage done because of preventable maintenance.
Greg L