Carburetion ! Why My engine Does This?......

Reply Subscribe

Thread Tools

Search this Thread

Apr 14, 2004 | 07:45 AM

cigarxtc

Thread Starter

Postmaster

Joined: Apr 2000

Posts: 2,881

Likes: 1

From: North of Tulsa, Oklahoma

Carburetion ! Why My engine Does This?......

When the screw in carb fuel filter gets clogged the engine will start and idle with no problem. I can even gun it in neutral or parked and the engine does not miss a beat. But when I put her in gear and give her gas she'll bog down or sputter and sometimes die. When it happens I just change the fuel filter and open the old one just to see what kind of crud is in it. I was just curious as to why, when the fuel filter is clogged, it would idle in neutral but when in gear it almost kills the motor? Does it have anything to do with the vacuum line from the manifold to the transmission? Or something else in the design of the stock 351m/c6 combo?

Apr 14, 2004 | 08:21 AM

73Custom

Postmaster

Joined: Apr 2000

Posts: 2,838

Likes: 6

From: SD

I would guess the filter allows just enough fuel through to keep it idling. In gear, the extra load or tip of the engine must be enough to kill it.

Marty

Apr 14, 2004 | 08:43 AM

biggreen78

Senior User

Joined: Jan 2004

Posts: 304

Likes: 0

i have the same vehicle and problem i have notice that there are 2 hoses in the same fitting not connected to anything-1 is attatched to the air filter, and the other im not sure (im at work and can't look right now) they are just hanging there. i think its part of the emmissions equipment could this be related to the sputtering?

Apr 14, 2004 | 09:22 AM

cigarxtc

Thread Starter

Postmaster

Joined: Apr 2000

Posts: 2,881

Likes: 1

From: North of Tulsa, Oklahoma

Marty, That's what I thought at first also, but when idling I can gun the engine to red line with no problem. That means a substantial amount of fuel is getting to the carb in neutral. That theory might not fit.

biggreen78, I don't have the EGR emmissions stuff and all hoses or vacuum plugs are present and accounted for.

My trucks runs great. I'm just perplexed as to why the clogged fuel filter causes my truck to do that? I'm just

one of those people that likes to know how things work and what makes things tick.

Apr 14, 2004 | 10:33 AM

beartracks

Lead Driver

Joined: Nov 2000

Posts: 6,625

Likes: 342

From: Albuquerque

It takes a lot more fuel to rev in gear. Power circuits open plus the back two barrels on a 4v. If your filter is clogging all the time you should consider dropping the tank and checking/flushing it and the lines. Original fuel lines/pumps are somewhat marginal to start with.

Apr 18, 2004 | 02:29 PM

Polkat

Elder User

Joined: Aug 2002

Posts: 662

Likes: 0

From: CA

Beartracks has it. When theres no load on the engine, the only work it is doing is spinning itself, and it can do this at surprisingly lean mixtures. Sounds to me that you should think about why that filter gets clogged so often. Problem in the tank?

Apr 18, 2004 | 05:59 PM

pops_91710

Laughing Gas

Joined: Jun 2003

Posts: 1,166

Likes: 0

From: Chino, California

Polkat,

You are right on. Several years ago I had the same problem. The dinky fuel strainer at the carburetor's fuel inlet constantly loaded up with tiny reflective metallic particles. To this day I do not know what it was, but it was a cinch it was some type of contamination from the tanks. I simply added an inline filter closer to the fuel tanks and gutted the little strainer at the carb several months later to insure the problem wasn't mid-stream. The truck is still running today and I change the filter every three years. Never had a lick of problems since.