Chevy TBI Guru's...need a little help - Page 2 - Off-Road Forums & Discussion Groups

CJ7Taz · #11 10-01-2009, 10:07 AM

Yeah, where the pump is mounted is not good. It should be mounted lower, like on the inside of the low part of the frame rail.

These pumps don’t have a good foot (suction side lift) but a fair head (pressure side push). Yeah, it still has to pull the fuel up to the top the first time to fill the empty line (a full tank will help with that) but after that, siphon action helps keep the fuel fed to the pump from the tank.

Caver Dave · #12 10-01-2009, 10:20 AM

Thoughts...

- You've changed the post pump filter?
- Have you confirmed pressure & Flow?
- Is the pump staying energized (getting 12VDC)

Not sure this matters, BUT... when I did the TBI swap, everything I read said to mount the pump as low as possible & the use of a pre-pump filter was beneficial. Most folks running inlines had either already had failures or knew they would and carry a spare. Mines (fleabay $30 "E2000" clone) got >250 miles on it and it's already noticeably noisier, so a spare is in my near future also (may try to grab an OEM Ford pump at the JY). I ended up with a connector in the pumps 12V+ wire that allows me to run the pump off the battery (independent of the ignition & ECM) for troubleshooting, priming, & emptying the tank if need be...

WILL · #13 10-01-2009, 05:30 PM

Yeah, electrics don't like to suck. Mine is mounted to the skid plate next to the gas tank and has never had a fuel starving issue.

bleoh · #14 10-05-2009, 12:09 PM

Quote:

Originally Posted by Caver Dave

^^I believe this is wrong^^... the injectors receive a full 12VDC (from usually from a fused/relayed source) and the ECM breaks/makes the ground (via D14 & D16) to fire them.

As I recently finished the TBI swap on the Moss, this stuff is fairly fresh in my mind. The first step to intelligently troubleshooting is double checking the obvious! Confirm the connections are good, that fuel pressure & flow are within spec, & that no codes are being thrown.

Do you own (or have access to) a code scanner or an ALDL cable/laptop?

These are low-z injectors. I think GM used current limiting to keep from overheating the ECU. So they get fed 12v and the ECU controls the ground path but limits the current after the initial opening of the injector.

JeepDawg · #15 10-05-2009, 01:16 PM

At this point I'm pretty sure the issue is the pump.....

From what I am reading it would appear that maybe the Carter I have is not the best choice....

Anyone have any suggestions?

I want to stay external for obvious reasons (like, not having to pull the tank).

Jim_Lou · #16 10-06-2009, 11:14 AM

My brother has had a rash of fuel pump problems with his motorhome, and I've done a little research on the issue. What I've discovered is that almost all replacement in-tank pumps for GM vehicles are made by either Airtex or Delphi. Delphi makes most of the Delco pumps. Airtex makes a few for Delco, but they're branded with the Delco logo. Apparently most no-name and off-brand pumps are Airtex.

And in a nutshell, Airtex pumps are lousy. My prime source has been in the parts business for about forty years and says that knowledgeable mechanics won't take an Airtex pump, even for free, because they'll have to replace it soon.

My brother got an Airtex-labeled pump which came out of a Delco box (there may be fraud involved.) It only lasted about 500 miles, where the one it replaced lasted 115K, and the Delphi that replaced it has gone several thousand so far.

May not be applicable to external pumps, but worth considering.

Caver Dave · #17 10-06-2009, 12:16 PM

That's why I skipped the "brand hype" and went with the $30 fleabay pump (since it's likely they all came from the same manufacturer)... at that price, I can afford to keep 2 spares and change them (>10 mins on my rig) 2:1 over the "branded" pumps!

OTOH, if you can find a Holley pump (more expensive, but reportedly quality pumps depending on *who* you talk to) in the correct pressure...

You might also have better luck using a "genuine FORD" E2000 ('80 something 351 & 460 equipped trucks), but likely to now be sourced from Bangladesh too!

JeepDawg · #18 10-06-2009, 02:23 PM

Update.................

I pulled the pump....hardly sucking at all....I can siphon gas through the line so I know that is good......

And there is a good reason I buy my stuff from NAPA.....even though it has been about 4 years since I bought the pump....they are replacing it for free....

I did some research on the internet....a lot of people swear by the Carter P5001....the general statements are that it's a perfect fit for TBI using an external pump.

The guy at NAPA did say that he thinks it failed to to lack of use....he might be right....at times the jeep sat for 2-3 months without running....I doubt I have more than 2000 miles on that pump....

Have you guys heard of something like that?

WILL · #19 10-07-2009, 10:42 AM

My pro-jection came with a Carter pump. It died at one point and I found a "NAPA brand" pump made by Carter that is the same pump. It has been on there for about 5 years. My jeep sits for months at a time too but I don't think that shortens the life of the pumps since it is low enough to keep fuel in the pump. Yours may be shortened just because it is high and the fuel drains out.

LEVE · #20 10-07-2009, 11:22 AM

Fuel will cause varnish to build up on thses pumps. When the pump in inactive for a long period, yes, they will/can fail. You may be able to recove the pump by attempting to suck straight Seafoam through it to clean it up. I'd also advise Seafom in a tank of fuel every 6 months, or so, to keep the varnish build up at a minimum. That will minimize chances of failure.