Weakness Revealed in the GMB and Spectra Mechanic Fuel pumps

[zKars]

I have another case reported today from a local customer with a <100 km use new Spectra pump that failed. 

Fortunately it was initial warm up in his garage, not on the road, but that was just pure luck. He was on his way to a wedding (not his at least) but was anxious to show it off to family members. Very disappointing.

I'll have that rotten pump and the Z in my shop tomorrow. I will thoroughly diagnose the issue with the pump and let you know what I find.

 

[Zed Head]

Weren't the fuel pump companies looking in to this?  Whatever happened with that?

And how about those pictures?  Probably got disappeared when Mike went back to the old format, whenever that was.  They gotta be on a server somewhere.  @Mike

There's a lot of value in this thread, stopping Z cars from dying dead.  

[zKars]

The pictures are on my phone somewhere. I'll do more to spruce up the thread when I find out details on this pump tomorrow 

I was doing a bit of research again on what's out there, and wanted to share the current status of what RockAuto sells.

The GMB, US Motor Works and Delphi are shown as having the OEM look, but look at that price difference! 

GMB is free is $18 buck, where as the USMP is $72!! Maybe it has quality innards.   yeah, right.....

Edited August 16, 2020 by zKars

[Zed Head]

Interesting that Delphi and Spectra are out of stock.  Sometimes that means discontinued.

[zKars]

Pictures are back. 

[zKars]

Ok, I have a clue! Highly unexpected, but true.

What I need is someone with a failed Spectra or GMB mechanical pump that is willing to take the top cap off and tell me what they see. 

Don’t take it off without marking it’s position relative to the body first!! Very Important!!!!

Anybody?

 

 

Edited August 18, 2020 by zKars

[David Downs]

48 minutes ago, zKars said:

Ok, I have a clue! Highly unexpected, but true.

What I need is someone with a failed Spectra or GMB mechanical pump that is willing to take the top cap off and tell me what they see. 

Don’t take it off without marking it’s position relative to the body first!! Very Important!!!!

Anybody?

 

 

I have taken a few apart to rebuild some Kyson Denki pumps. Enlighten us on what you expect us to see. I can tell you when I removed one of the caps on a GMB or Delphi the top of the rubber gasket was wet (one side only). I believe this pump failed because the gasket didn't seal properly around the cap screw. One of the other pumps had a bad check valve and you could see the seal damage.

[Trnelson]

Following, I’m new to this game so excuse me if I sound uneducated. I cannibalized a GMB pump for the diaphragm and check valves to install on my Kyosan Denki as a preventative maintenance measure. Drove about 25 miles with no issues on the test drive yesterday. Cranked the car today, fired right up, ran about one minute and died. Tried to start it a few more times to no avail, took the outlet line loose and no fuel came out while cranking. Was running late for a tee time so that’s as far as I got. I will say the GMB parts did not feel of the same quality as the originals I pulled out. Thankfully I saved them and will be reinstalling them tomorrow. 
 

[zKars]

Ok, what I think the issue is that the top cap is installed at the factory 90 degrees wrong, The internal center rib on the cap MUST be aligned with the mating center rib between the two check valves. Having the cap on with the ribs crossed allows flow to sneak through that upper diaphragm. This was the case with the one I looked at today. Turned the cap 90 and put it back on, and boom. Perfectly functioning pump. 

I wanted others with failed pumps to take the top off and see if the factory has the ribs aligned or crossed.

My guess is that from the factory, the diaphragm is sticky enough in some way to limit the leak, but eventually and quickly the dam bursts and that’s it  No more suction. At least that’s today’s theory. I need someone else to find the same flaw.  

Secretly I ordered three more GMB pumps from RockAuto today (can’t beat $17.83 CAD each!) to see if any or all have the flaw. Is it random or is the assembly line guy/robot slapping them together. however they like?

Edited August 18, 2020 by zKars

[Zed Head]

49 minutes ago, zKars said:

Is it random or is the assembly line guy/robot slapping them together. however they like?

You know it's rural people, who probably don't know 90 from 180, in a warehouse in Asia.  Certainly no robots.

[Zed Head]

On 8/16/2020 at 2:03 PM, Zed Head said:

Weren't the fuel pump companies looking in to this?  Whatever happened with that?

Here is what I remembered.  It was Carl Beck.  @Carl Beck

 

[SteveJ]

7 hours ago, zKars said:

Ok, what I think the issue is that the top cap is installed at the factory 90 degrees wrong, The internal center rib on the cap MUST be aligned with the mating center rib between the two check valves. Having the cap on with the ribs crossed allows flow to sneak through that upper diaphragm. This was the case with the one I looked at today. Turned the cap 90 and put it back on, and boom. Perfectly functioning pump. 

I wanted others with failed pumps to take the top off and see if the factory has the ribs aligned or crossed.

My guess is that from the factory, the diaphragm is sticky enough in some way to limit the leak, but eventually and quickly the dam bursts and that’s it  No more suction. At least that’s today’s theory. I need someone else to find the same flaw.  

Secretly I ordered three more GMB pumps from RockAuto today (can’t beat $17.83 CAD each!) to see if any or all have the flaw. Is it random or is the assembly line guy/robot slapping them together. however they like?

Could you take a photo or two and post here? I have one I can take apart.