willysmjeeps.com

Since I'm installing a civvy fuel / vacuum pump I posted this on earlyCJ5.net but got no response. Since the smart guys hang out here, maybe someone on this forum can help

This was my post: I'm going to replace my mechanical fuel pump with a dual action AC 9526 so I'll have more reliable vacuum to operate my wipers. I also plan to reinstall the PCV valve which disappeared sometime during prior ownership.

I've seen some pix of similar pump installations here and there but I still have some confusion. Since my pump came with no instructions, I'm turning to you.

First, before you ask, I do have the 1/8th inch spacer for it.

Let me know if I have this right - looking at the attached pix, my understanding is the top section is fuel and the bottom is vacuum. Port A on the top is connected to the carb while port B is connected to the fuel line from the fuel tank.

On the bottom, port 1 (labeled IN) is vacuum and is connected to the wipers. Port 2 is pressure (out) and is connected to a fitting on the manifold below the carb. Along the way it is Tee'd off to the PCV valve which in turn is plumbed into the side valve cover.

How am I doing?

Tim

You got her upside down Tim. The flat top is the fuel side. I would have to look at mine and deduct some ports for the fording system to answer the port location question.

Here's the original M38A1 setup



Here's my 60 CJ3B

Your pump is not indexed correctly. The vac line ports should face the rear of the jeep. But you can still use my CJ3B illustration to sort out your ports.

Now you know why I asked - the markings on my pump did not seem to match what I was able to glean from the other info I found.

Madmike, I am holding the pump right side up.... it doesn't match up to the military pump very well. The fording system on my engine is disabled so I don't need the extra ports. Funny thing, I have two Jeeps (a runner and a parts Jeep) and neither one of them had a dual action pump.

Wes, if I have this right, A is fuel in - B is the fuel line to carb - 1 is the line to the intake while 2 is connected to the wipers.

Thanks to all!
Tim

As compared to my 3B pump your analysis is correct.

The reason many jeeps have single action pumps is because the fording system was discarded and the owners switched to electric wipers thus the dual pump was an uneccessary additional expense.

Well that is interesting. The pump can be used either direction. You knew it was oriented correctly by the pump arm which I could not see. I just rebuilt mine and while checking for suction coming from the correct ports, I asked myself the question about why it seemed the pump could be used either way. Didn't get an answer so I promptly forgot it like most things anymore.

This is why I should stay out of discussions in areas that I have limited experience. The obvious ain't always so.

Mike

Madmike - I knew which side of my pump was up based upon the orientation of the mounting flange. As I said, I had no installation instructions and was unsuccessful at getting definitive info off the internet. There is a lot more info out there on your military pump than my civvy version. I wish I had a good M38A1 pump but this civvy one should do the job. Since my jeep has a 12 volt non-waterproof electrical system (with alternator) there is no way it will ever look original so the pump I have is good enough.

Wes - thanks... I always appreciate you taking the time to share your knowledge with us newbies. I'm hoping the pump does the job... I recently obtained a pair of NOS wiper motors so I hope to have functional wipers when all done.

Tim

wesk wrote:As compared to my 3B pump your analysis is correct.

The reason many jeeps have single action pumps is because the fording system was discarded and the owners switched to electric wipers thus the dual pump was an uneccessary additional expense.

I'm resurrecting this thread rather than starting a new one. If the fording system is no longer used, how should the vacuum line from the side of the block through the PCV valve be routed? What is it's end point?

It is unfortunate you chose not to open this as a new topic. A couple of years from now when someone has a question about your addition a search of our old posts will not offer this one up under the topic How to run vacuum tube from PCV valve without fording system.

With that said lets try to see where you are coming from and want to go. Do we assume you are aware that the fording system is a small part of the vent system and the vent system exists in one of two forms on all M38's and M38A1's.

The items normally associated with the fording system are the Kit which has the two pipes and the two shutoff valves added to the vent system. How these are plumbed depends on which model jeep you have and how much of it's vent plumbing is left. You will have to offer us this information and photos of your engine compartment's current vent plumbing so we can offer you one reply.

wesk wrote:It is unfortunate you chose not to open this as a new topic. A couple of years from now when someone has a question about your addition a search of our old posts will not offer this one up under the topic How to run vacuum tube from PCV valve without fording system.

With that said lets try to see where you are coming from and want to go. Do we assume you are aware that the fording system is a small part of the vent system and the vent system exists in one of two forms on all M38's and M38A1's.

The items normally associated with the fording system are the Kit which has the two pipes and the two shutoff valves added to the vent system. How these are plumbed depends on which model jeep you have and how much of it's vent plumbing is left. You will have to offer us this information and photos of your engine compartment's current vent plumbing so we can offer you one reply.

Point taken, Wes. I'll start a new topic.