garretthes

LM7 from 2004 Silverado with stock intake etc. I have gone through two fuel pumps in 14 months. I modified the 59 factory tank with a return line and use an inline pump with the fuel filter/regulator assembly.
I am wondering if I will have to install a sump in the tank? Or is it just bad luck on the inline pumps?

MeanYellowZ

iTrader: (19)

If you are pulling from the top of the stock tank in the cab it is hard on the inline pumps. You have a few options, including using a low pressure transfer pump that is okay picking the fuel up like that. Just make sure it can flow the same or more in gallons per hour (or whatever measurement you want to use) than your inline injection pump.

Otherwise sumping the tank, going to a cell etc are going to be your options. BTW, I am building a 59 now myself

G-Body

iTrader: (4)

If you have a 5/16" pickup in the tank you will keep burning up pumps, its too restrictive. Even a 3/8" is probably too restrictive. You might be ok if you have a half inch pickup in the tank. Most of the high pressure pumps really do not like to pull the fuel to them. Thats why I like to run internal pumps.

garretthes

Not completely sure but I believe I ran my new plumbing the same diameter as the 04 lines running to the fuel rail. I did use a stock sending unit so that could be a bottle neck. Should I retrofit a modern in tank pump to work? I have no clue where to look for a 1/2" pickup tube for this tank! Any ideas?

I'm purchasing (or Advance Auto is warrantying) the next size up in pump specs. I think he said it was 100 psi but I can't remember the flow.

garretthes

Here is a link to my journal with pics of the lines. I think I used 3/8 line to match the stock.
http://www.hotrodders.com/forum/jour...age=5&reverse=

bczee

iTrader: (12)

You didn't state what brand and spec's the pump is.

Being a external and inline... heat has been the most common cause of failing pumps, vibration is another cause that can add to them failing.
If the pump is not mounted in an area where it can be cool by air flow or it is close to the exhaust system. Along with what else everyone has stated about problem, It can cause it to over heat and fail.

Pop N Wood

iTrader: (1)

How are they failing? Getting clogged with debris, won't take current anymore, seizing up?

garretthes

Seizing up. The 1st pump whined for a few months then died. The second pump started whining after setting in a traffic jam for 20 minutes. The pump is mounted on the frame under the pass seat away from the exhaust. It is possible there was debris in the tank. I did drill a hole for the return line. I spent over half an hour with a magnet running along the bottom until I was sure there were no shavings left. Besides, there is a sock on the sending unit. Is there a way to check the 1st pump for debris? I still have it.

cooks 7

Is your tank vented at all? The whining after sitting in traffic sounds like it built up heat and possibly had vapor lock issues. Something else to look at.

Pop N Wood

iTrader: (1)

I had my first pump sieze up on debris. I was able to take mine apart with a screwdriver and get to the georotor. I cleaned it out but is was so badly scored that I had to replace it. Kept blowing fuses. I replaced the pump with a cheap rotary vane pump and an expensive prefilter.

You might try backflushing the old pump, see if anything comes out. If the old pump is truely toast you can almost certainly pry or cut it open. You never did say what brand/model pump you had.

IMO a sock isn't going to do it. Get a nice low restriction prefilter you can open up and clean out.

rtpassini

there have been lots of people who run in line pumps without problems...I wouldnt think it was the pump. unless it was a cheapo pump or something.
Im probably going to be running a ZEX booster pump.

garretthes

The gas cap is far from air tight but there is no vent.

Also, I discovered an engineering flaw today. We originally plumbed the fuel lines with a return coming from the fuel rail. I installed an in line fuel filter just after the in line pump. Then we realized we needed a filter/regulator for this setup so I installed it at the fuel rail. Well I totally forgot the other filter so I have been running two filters.

garretthes

Sorry, forgot to answer the model question.
The 1st pump was an MSD. The second and now 3rd are airtex.

rtpassini

so do you all suggest running a filter BEFORE the fuel pump and then also one after such as the corvetter filter regulator setup?

G-Body

iTrader: (4)

You should use both a pre and post filter. The fuel should be filtered with a 100 micron pre filter and then you should have a 10 micron filter after the pump.

eric1967

I am having pump problems also. I have a Rick's Tank with a walbro pump in a 67 Camaro. I have checked voltage. It runs 13.5 to 14 volts everytime I check it. When I start it it will have 58psi but as it runs it drops down to about 52. I was using the corvette bypass filter, but I switched to a bypass regulator. I start having trouble after about 2000 miles.

garretthes

Update:
After doing some research I changed the location of my pump. It was too high and too far forward. Now it's sitting level with the bottom of the tank mid way front to back. Gravity is an inline pump's friend.
However, it still whines after running for a while so I'm expecting this one to fail. My plan is to fabricate a custom tank with baffles and make it larger than the stock 14 gallon tank. I will use the collar and stock in-tank filter from an LS powered vehicle. I discovered a 2005 Suburban tank is the same depth that I want to build mine so the sending unit will work.
Just need some time.....

On another note, what's the gph and pressure rating for the LM7?