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More fuel pump woes.

Vhyle

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So if you've been following my posts in the "What have you done to your CUCV" thread, you probably remember my fuel pump issues I've been having.

To recap: I installed a new fuel pump because the old one was leaking. The replacement pump is a Precision brand pump. During the install, I made sure the pushrod was recessed completely in the block, so I can install the pump properly. I used grease on the rod so it would stay in place.

I also had to replace the fuel injector drainback tube, because it broke from rust and corrosion.

Got everything back installed and ready to go, and I went to turn it over to start bleeding the system. It just wouldn't bleed. It wouldn't even think about starting. I was getting nothing through the fuel filter.

(this is all over a span of a couple of weeks, mind you, because of super-late work days and abysmal weather that I just didn't want to deal with)

So the other day, I decided to remove the rubber hose (which was also replaced during the pump install) from the line coming from the tank, and tried to funnel some fuel into the pump, in hopes of priming it somehow. I filled up the funnel tube, and then tried to turn it over again. It turned over and over, but the pump didn't suck in one bit of the fuel. So then I determined the pump itself isn't working. Next step, of course, is to remove the pump and see what's going on. Maybe the pump is crap, or maybe the install went wrong somehow.

So tonight, since the weather was decent, I pulled the pump back off.

The pushrod broke clean in half! Perfect break, almost dead center. Two clean pieces. Once I removed the pump mounting plate, the bottom half fell out. The top half was actually still in the journal, being held there by the grease I used during the install. I used a magnet to retrieve it, and it slid right out. I think this is kinda odd. There's no damage to the block (as far as I can tell). Just a perfectly snapped pushrod.

Now, a few observations I had during all this: the new fuel pump is EXTREMELY stiff. Like, I couldn't actuate it by hand unless I was immortal. The old one pumps with ease. Of course, it's old and has some wear and tear. So I figured it was normal for new pumps to be so stiff. Plus on top of that, the pushrod is 27 years old and has been exposed to many many many cycles and lots of heat, and perhaps developed a weak spot in the center. The new pump just finished it off.

Maybe the install went wrong? Maybe I put pressure on the pushrod during the reinstall without realizing it, and broke it after it was all back together?

Manufacturer defect? I doubt it though, because I've never heard or read anyone else with a 6.2 that experienced this.

Maybe I just have dumb luck?

Anyways, check out the pics. My plan is to get a different pump; probably AC Delco brand. As far as the pushrod, I'll simply make a new one! I make my living in a machine shop. Making a new one of these would be cakewalk.pushrod_1.jpgpushrod_2.jpg
 

patracy

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Do yourself a favor. Toss the mech. setup in the trash and install an electric pump. You'll thank yourself the first filter change.
 

Vhyle

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You're probably right. That would be a good move.

But right now, I'm intrigued by this. I want to know why the crap this happened. It's just weird.
 

Hasdrubal

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I've read several threads here where people have broken the pushrod. It always baffled me how a piece of steel could break in two, what forced this to occur? Never was resolved by anyone as far as I know. Seemed to recall they just tried a new pushrod and another pump, perhaps the pump was defective? A new pump is too stiff to attempt hand operation.
 

Recovry4x4

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I'm not completely sold on the electric lift pump deal. I know they make bleeding a snap and any leaks in a pressure line drip fuel vs a suction line that just draws air. I've never had any difficulty priming a system with the mechanical lift pump when changing a filter. I also don't have any particular problems with the Stanadyne 80 filter base but many just loathe them. I had to prime my 1010 many times over the weekend looking for an air leak and it primed easily with the mech lift pump. With that said I'm switching all of my trucks over to the FM100 base solely as an economic decision. With the dump of thousands of elements on the market, I can buy the bases and a lifetime supply of filters for the price of 12 box filters.

Pump rod. They are very intolerant of and side load pressure. They have to be as they are made of a material compatible with the camshaft. It would be very easy to break that rod during the install. Any extra or replaced cams we had were always thrown up in the air so we could watch them break and bet on how many pieces they would break into.
 

dstang97

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I have run an electric fuel pump before and never really liked it. One thing I really love about these trucks is it pretty much all mechanical.
 

MarcusOReallyus

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Do yourself a favor. Toss the mech. setup in the trash and install an electric pump. You'll thank yourself the first filter change.
You're probably right. That would be a good move.

But right now, I'm intrigued by this. I want to know why the crap this happened. It's just weird.

So put in the electric to get running and investigate the failed new pump to satisfy your curiosity. :-D

Best of both worlds! :beer:
 
481
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Location
Charlotte, MI
Vhyle, I figured you'd find a pushrod problem once you pulled it apart. Like recovery4x4 said, these rods are so hardened they don't tolerate side loads. A stiff pump will not break these rods as it takes side pressure not straight pressure. Something went wrong during installation. Perhaps the pump arm came off the rod before tightening? I don't know these diesel blocks well, but some sbc blocks have a short bolt on the front towards the rod. You take that out and use a longer bolt to hold the rod in position during installation. As far as making your own rod, make sure it is hardened like the original or you will wipe out the rod or the cam, hopefully just the rod.

Anyway, thanks for the post and update.

Mike
 

Recovry4x4

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I have a general policy that I buy parts when they are readily available, rather than make them.

In this case, for $13, why make one?

http://www.gmpartsdirect.com/results.cfm?addtocart=1&addpartnumber=14050425&singlepart=1&partnumber=14050425

BTW, just one guess where I found the GM part number...
I don't know about you but I get GM part numbers from the TMs. Just got in one order from parts direct for spare tire carrier parts. It's amazing what you can find with your fingers and 10 minutes. The other part was no longer available but the evil auction place had a new one!
 

Vhyle

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I looked up up the p/n in the TM before I made the thread. But on second thought, I probably will just buy one. I could make one and harden it but it's so cheap, buying one would just be easier.
 

Skinny

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Genuine AC Delco fuel pump on RockAuto was something like $30 shipped to my door. Perfect fit and seems like very nice quality. Just thread the steel line into it first before tightening it up to the block.
 
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