1970 Challenger 440 Fuel Issue

[jcbruce]

Runcharger - Not understanding what you are saying (my fault).  We think the fuel pump is fine (including the pushrod attached to it).  What we think it that the cam inside the block is not rigid enough (for some reason) to open the valves in the fuel pump via the fuel pump pushrod.

Are you saying there is a way to get that cam out (or inspect it) without opening the front of the block up?

My understanding is that cam is held in place with a bolt that you can't access without the front plate of the motor off.

We can't get back to it until tomorrow so there is some time to think about this.  We don't want to open more cans of worms than we need to but not sure how that cam can be accessed without getting to that bolt.

Sorry if these comments don't make sense, we are learning as we go here.

[Chryco Psycho]

The pushrod rides directly on the camshaft

[YellowThumper]

If the pushrod itself is worn significantly.  Then it will not properly actuate the fuel pump lever. The rod will still follow the cam lobe but overall push, retract, push, retract movement will be reduced. Rod must be proper full length to move pump lever fully.

[JonH]

Wow this is all over the place. There is a pushrod that rides on the camshaft and pushes the lever on the fuel pump. This pushrod wears. This is what Chryco is talking about. NOT the camshaft or anything else. Look at the video link below. About 9 minutes in you can see exactly what he is talking about....

https://www.bing.com/videos/search?q=440+fuel+pump+pushrod+removal&view=detail&mid=F5E708A02BAB509389BBF5E708A02BAB509389BB&FORM=VIRE

[Chryco Psycho]

You have to remove the pipe plug below the fuel pump & Slide the pushrod out , there is a reduced diameter on each end of the pushrod they should be the same length

[Chryco Psycho]

Here is a picture of the rod

[MEK-Dangerous]

Here is a test. If you can remove the fuel pump from the block and re-install it again easily, your push rod is worn. I've been down that road. I bought a new push rod, and found the one that I was using was 1/8" shorter. No problems after that.

My issue was the fuel pressure was fine at start up. After everything got warm, fuel pressure would tank if I floored it. By tank, I mean I was looking at almost zero PSI, until I let off the gas. As a side note, I installed an after market fuel pressure gauge inside my car at that point just to see what was happening and when.

[dodj]

How would a worn fuel pump push rod work fine when cold but not when hot? 

[RUNCHARGER]

As MFK states, the engine is cold so you let it idle and drive it gently, the fuel bowls are filled up with this scenario. Then the engine is hot and you get on it a bit or even just rev it a bit, that uses more fuel and drains the carb fuel bowls.
I'm not saying the camshaft couldn't be flat, it's much more likely the rod is worn and it's so easy to check it without evasive surgery.
That's it for me though. Feel free to tear down the engine or whatever you wish to do.

[dodj]

As MFK states, the engine is cold so you let it idle and drive it gently, the fuel bowls are filled up with this scenario. Then the engine is hot and you get on it a bit or even just rev it a bit, that uses more fuel and drains the carb fuel bowls.
I'm not saying the camshaft couldn't be flat, it's much more likely the rod is worn and it's so easy to check it without evasive surgery.
That's it for me though. Feel free to tear down the engine or whatever you wish to do.

Ah..that makes sense.

[jcbruce]

Well, I really appreciate all your comments, and thanks to the pictures and video, I get it.  I actually had started watching that same video but didn't watch it all the way through.

We will take out that freeze plug tomorrow and pull the old push rod.  I will post a picture.  If we order a new one is there any adjustment we need to do, or is it good to go as is?

The scenario that MEK Dangerous describes is exactly like mine.  It was fine when we started the car but as it warmed up, and especially when I juiced it, it lost fuel.  We thought it was heat related, thus got on the vapor lock trail.

I definitely don't want to open anything I don't have to.

So, will let you know tomorrow.  Again, I really appreciate the help.  Learning.

[Chryco Psycho]

I would coat the pushrod with grease so it will stay up out of the way as you install the fuel pump nothing else is needed

[jcbruce]

Well, we got back to it today.  Thanks to all of you (including pictures and videos) we sort of knew what we were doing.  Took the freeze plug out under the fuel pump (which was already out).  And.   The push rod did not come out!  Would not come out.  Even after some serious pulling.  We took the distributor out so we could see the cam side of the rod better.  We bought a borescope so we could see in there.  The "top" of the push rod was flat as a nail and mushroomed out with scoring across the end.  Looked baddd.  We then spent the next hour or two fighting to get it out.  Just did not want to budge.

We won.  It's even more mangled by us getting it out (or I would post a picture).  Thanks to Runcharger, I ordered a replacement from 440.com.  Guy said they are the same length, ect.. and told me its a fit.  Looks like it on the website.

So Chyrco, its looks like you were right from day 1 AND I told you this is a rotissorie car.  When we looked at the gears we could see they look brand new.  I'm thinking like you said they rebuilt this motor and just didn't put a new $13 push rod in.

Should have the part in a day or so, will put it in and update.  But, we have the culprit.  Appreciate the help and hopefully finish this tread (successfully) next update.

[jordan]

And Neil wins another round of "Guess my Problem".   You save everyone around here.  You are a Mopar Hero!!  This site is lucky to have you here.  I learn so much just by following along.  Thanks

[Chryco Psycho]

You know this But believe it or not I have seen this before , a customer had a Charger with the same issue , he lived with the same problem for a few years , took it to a number of "mechanics" finally I talked to him at a car show about the issue & he had me look at it , in minutes I had the problem solved as I had brought a new pushrod with me . I have never seen one as bad as yours tho , usually they wear down but still are able to slide out .
Anyway I am glad you have found the issue & are well on the way to fixing it 
1 suggestion is Make Sure you are using SJ or Gibbs or Penn high Zinc oil otherwise you can lose this pushrod or even the cam itself !