Losing prime to gas tank...........

Reply

  #1  
Old 11-18-06, 10:59 AM
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 390
Losing prime to gas tank...........

I have a 1987 Chevy 4x4 Blazer, I use it to plow my driveway. Fuel pump went, put a new pump in and gave it a total tune-up. My problem is, every time I turn off the truck, it won't start again unless I prime the carb. I let it run, turn it off, then try to start it again, nothing. If I put alittle gas in the carb, it'll start up. I checked for gas line leaks, can't find any. Can you lose prime that fast? There isn't much gas in the gas tank, maybe 5 gal max. Would this cause the problem? Any advise would be a great help...........
 
Sponsored Links
  #2  
Old 11-18-06, 11:40 AM
Member
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,700
What is the setup on the fuel pump/engine? Is it an electric in the tank with fuel injection nossles in the carb throat? Or is it a mechanical fuel pump and a conventional carburetor?

If you have a conventional carb with float bowl, etc., you should have enough fuel in the float bowl to start the engine and the problem may well be in the carb. If you have a fuel injection system with a pressurized fuel rail the problem would likely be in the regulator that holds the pressure in the fuel rail.

It would be better to have more than 5 gallons of gas in the tank under any condition.

Let us know,

Bob
 
  #3  
Old 11-18-06, 01:11 PM
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 390
Yes, it is a electric fuel pump in the tank with fuel enjected carb. Where is this fuel regulator your talking about?
 
  #4  
Old 11-18-06, 03:21 PM
Member
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,700
You're getting back there a few years on this one. The pressure regulator is typically on the fuel rail the injectors feed from. The regulator's job is to provide a checkback on the flow from the fuel pump and maintain pressure in the rail. There's a possiblity the checking mechanism on that setup is in the fuel pump itself.

The electric solenoid on the injectors open the nozzle and the fuel is pressure fed from the rail through the injector.
See if there isn't a schroeder valve (looks like the end of a tire stem) on the line that feeds the injectors. That would be where you can do a pressure check on the fuel pump.

If you find that, turn on the key for about ten seconds and turn the key back off (be sure to turn the key back off). Then depress the release on the valve. There should be a small amount of gas spurt from the valve. If there isn't, it means pressure isn't being held in the rail.

If you find the latter is the case, you would have the equivalent of a carburetor without any fuel in it and you would to crank the engine enough to fill the float bowl each time you started the engine.

In your case, though, even without anything checking the backflow of the fuel, with the pump working, the pressure should build up in the rail(after a short period of time) and the engine should start.

Hope this helps,

Bob
 
  #5  
Old 11-19-06, 05:30 AM
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 390
I just remembered, after the fuel pump went, I poured some gas down the throttle body to see if the truck would run so I knew if the pump was bad or not. Well, I got a backfire and I had a flame in the throttle body. It took me a little bit to blow the flame out. I may have got the regulator diaphragm hot or maybe melted it. I'm going to rebuild the regulator and see if thats the problem. Anyone know where I can find a blow up sheet on line on how to remove the old regulator?
 

Last edited by grantiman; 11-19-06 at 02:11 PM.
  #6  
Old 11-22-06, 10:51 AM
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 390
Well, rebuild the fuel pressue regulator. The metal disc on the diaphram was very badly rusted and falling apart. Put it back together and the truck started right up. Thanks for all the help, I learn something new everyday.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'