Starts but quickly dies, any low tech tips for diagnosis?

[Backfoot100]

The trick to em is there's a bolt hole in the front of the block that should have a bolt in it that's just plugging the hole. You take out that bolt and put a magnet In there to hold the fuel pump rod, or take a longer bolt and lightly tighten it up on the rod and hold it that way.

Glad you got it figured out! Was probably only like 30 bucks too lol

+1
Last time I changed a mechanical pump on a SBC took a total of maybe 30 min. start to finish.
Easy as pie.

 

[78C10BigTen]

The trick to em is there's a bolt hole in the front of the block that should have a bolt in it that's just plugging the hole. You take out that bolt and put a magnet In there to hold the fuel pump rod, or take a longer bolt and lightly tighten it up on the rod and hold it that way.

Glad you got it figured out! Was probably only like 30 bucks too lol

I was unaware of this trick! Good to know. I always fight it up in there with my pinky finger then shove the pump in as i yank out my finger and hope for the best lol.

 

[CoggedBelt75]

THANKS FOR ALL THE SUGGESTIONS AND HELP! it was the fuel pump! got a new one on, and it fires right up and runs like a dream again. those mechanical pumps are a pain in the ass to put back on. took it off in 10 mins, and then it took like 2 hours to put the new one on! but its done

Thanks for posting the solution to your problem. Seems like a few people will come on looking for help for some problem they’re having, get a bunch of f possible fixes, and then they leave the thread open and everyone hanging if the problem was solved or not.

 

[78C10BigTen]

Im not guilty of that... any ive fixed ive posted any others... well they still aint fixed!

 

[Termite_Delight]

The trick to em is there's a bolt hole in the front of the block that should have a bolt in it that's just plugging the hole. You take out that bolt and put a magnet In there to hold the fuel pump rod, or take a longer bolt and lightly tighten it up on the rod and hold it that way.

Glad you got it figured out! Was probably only like 30 bucks too lol

Didn't know that trick, I was taught to use a hacksaw blade to hold the rod in place. I'll try your way next time.

 

[PrairieDrifter]

As far as I'm aware all blocks before the tbi years have this hole. But getting into the tbi year blocks, just like the mechanical fuel pump rod provision, it may or may not be there. Seems to be a hit or miss in the 90's.

The last bit is only relevant to people swapping and what not as if you have a tbi truck you'll probably be sticking with the factory electric pump. Unless you're trying to swap from tbi to carb then you might be in or out of luck for a mechanical fuel pump

 

[78C10BigTen]

As far as I'm aware all blocks before the tbi years have this hole. But getting into the tbi year blocks, just like the mechanical fuel pump rod provision, it may or may not be there. Seems to be a hit or miss in the 90's.

The last bit is only relevant to people swapping and what not as if you have a tbi truck you'll probably be sticking with the factory electric pump. Unless you're trying to swap from tbi to carb then you might be in or out of luck for a mechanical fuel pump

My 94 gmt400 burb had a 350 with the manual pump block off plate on it. I had argued that this was correct many times.

 

[PrairieDrifter]

My 94 gmt400 burb had a 350 with the manual pump block off plate on it. I had argued that this was correct many times.

I believe all the blocks have the block off plate, but not all of them have the shaft provision for the fuel pump rod.

 

[78C10BigTen]

I believe all the blocks have the block off plate, but not all of them have the shaft provision for the fuel pump rod.

Ive never had the plate off to look...

 

[PrairieDrifter]

Ive never had the plate off to look...

If it's not leaking oil from there then it probably doesn't lol.

 

[Bextreme04]

I'm having almost the exact same problem. I have completely rebuilt the fuel system within the last few months. New sending units, fuel pump, and rebuilt factory quadrajet. My issue sounds the same as the OP, except the truck runs very rich. I can't seem to get the idle tuned right and it is always running very rich. Recently it has gotten worse and now does the stall a few seconds after start-up. I hooked up a fuel pressure gauge and it turns out I'm getting ~9psi at idle that is then maxing the gauge out at 11psi when you rev it at all. From other posts I've seen that quadrajets prefer ~5psi and can have major issues with fuel pushing past the seat and flooding the carb at higher pressures than that, so I ordered some parts and will be installing a regulator, filter, and checkvalve between the pump and the carb to see if that fixes the issue. I'll check back in afterwards and let you know if it does.

 

[80BrownK10]

I'm having almost the exact same problem. I have completely rebuilt the fuel system within the last few months. New sending units, fuel pump, and rebuilt factory quadrajet. My issue sounds the same as the OP, except the truck runs very rich. I can't seem to get the idle tuned right and it is always running very rich. Recently it has gotten worse and now does the stall a few seconds after start-up. I hooked up a fuel pressure gauge and it turns out I'm getting ~9psi at idle that is then maxing the gauge out at 11psi when you rev it at all. From other posts I've seen that quadrajets prefer ~5psi and can have major issues with fuel pushing past the seat and flooding the carb at higher pressures than that, so I ordered some parts and will be installing a regulator, filter, and checkvalve between the pump and the carb to see if that fixes the issue. I'll check back in afterwards and let you know if it does.

Are you useing a mechanical pump?

 

[Shorty81]

The trick to em is there's a bolt hole in the front of the block that should have a bolt in it that's just plugging the hole. You take out that bolt and put a magnet In there to hold the fuel pump rod, or take a longer bolt and lightly tighten it up on the rod and hold it that way.

Glad you got it figured out! Was probably only like 30 bucks too lol

Just remember when the fuel pump job is finished make sure you put the short bolt back in the hole in the block. About 30 years ago that bolt fell out of my 350 sb, and at cruising speed I lost 4qt of oil. But it would only leak over 30lbs oil pressure. Had a rough time tracking that leak down for there was oil everywhere.

 

[PrairieDrifter]

Just remember when the fuel pump job is finished make sure you put the short bolt back in the hole in the block. About 30 years ago that bolt fell out of my 350 sb, and at cruising speed I lost 4qt of oil. But it would only leak over 30lbs oil pressure. Had a rough time tracking that leak down for there was oil everywhere.

It's in the perfect spot to get oil everywhere lol. As with anything though, if you've got leftover bolts then your gonna have to go back and double check! Unless of course it decides to remove itself haha.

 

[PrairieDrifter]

Something else I just thought of, there's a drain hole in the bottom of that fuel pump cavity. So I'm not sure if that would be there all of the time either, just like the fuel pump rod shaft.