Finally Got Fuel Pressure Under Control And Now I'm Blowing Coal

I went through a few years of not really understanding how important fuel pressure is. I finally have it rock steady 4 psi and doing some long runs now. The jeep runs better than ever and very consistent. It used to lean out when the pressure dropped and way rich when the pressure shot up. I'm the second owner so I don't know how many years it was tuned incorrectly.

Now after running it the way it's supposed to it's spitting out little chunks of carbon. The other day it blew brown/yellow smoke for a minute. It runs great and this is usually on start up. Is the loose stuff just getting knocked off the valves and exhaust?

Been working on cars for many years. Never seen this before.

 

If it ran too rich for a lengthy period there would be some carbon build up, which may be loosening up now that the mixture is leaner. Brown/yellow smoke on start up sounds, if it clears after running a while is likely due to worn valve guides or valve guide seals. Which engine is in the Jeep?

 

Dauntless. I think it was carbon burn off. It never did that before and only blew smoke once the other day. I start it just about every day so I think a valve guide problem would be more gradual. The color was weird and didn't look like burning oil.

Thanks.

 

Could just be from the excess carbon burning off as you said.

 

Change the plugs, and give it an italian tuneup.

 

Lol. You mean use some snakeoil. Seafoam maybe?

 

Started it up the next day. No smoke at all.

 

Seafoam, Berryman, (hell, technically you can just use water) whatever, just pour it right down the carburetor. Doesn't really matter which one. Then take it out and just rod the hell out of it, get the RPM's up.

 

This is going to be fun.

 

Just to follow up my statement, that did mean "pour it down the carburetor, in small amounts while it's running" If you just pour a can of seafoam down the carb, and then try to start it, you're going to have a terrible day, and if you pour it too quickly, it will just kill (as in, engine shuts off, not breaks the engine) the engine. But it really will do a decent job of cleaning a fair bit of the carbon off of the face of the pistons, and the valves.

 

Buddy of mine in high school had a Model A, and it was always fouling plugs. He just poured a little water down the carb every now and then and it would run better for a few days.

 

Hey pappy, how'd he do that. I thought model A's had up draft carbs. I would think pouring anyhing down those carburetors would be tough.

 

They did have up draft carburetors much like the one on my old Ford 8N tractor. Even an up draft has an air intake.

 

Alright, so he poured water UP the carb...

 

What did you do to get the flow correct? Mine has always been wacky. It doesnt seem to be the pump its always a consistent pressure. I have 3 differet carbs I switch out sometimes. They all run differently none perfect

 

Here's the discussion.

67 Dauntless 225 V6 Fuel Line Upgrade | ECJ5 (earlycj5.com)

I finally went with a hard line to the pump, fuel filter just after pump (like factory), hard line to fuel regulator, fuel pressure sensor, carb. I also went with a soft line to return from carb to sender cap on tank. Drilled and tapped the sender cover. I will convert this over to hard line at some point. I found the biggest problem was running a fuel pressure regulator and vapor lock. You HAVE to get rid of the vapor lock. Return line is mandatory. Running fuel filter after pump helped a lot.

It's pretty drastic how much better it starts and runs. I would be wheeling and vapor lock would hit. Fuel pressure regulator would close (they don't work with vapor). It would run lean or die until it cooled down. I'd remove the regulator, be wheeling and when doing a slow crawl, the pressure would shoot up. Cheap pump wasn't able to self-regulate correctly and carb was overwhelmed. It would then run super rich and I don't know how many offroad sessions I had to turn around and go home pissed and just take out my dirtbike.

It now runs at 4 psi all the time. This was all verified with an on-board fuel pressure sensor. Between this and my overheating problem I was only able to drive when in winter or around town. Kinda makes sense. When fuel is flowing, ambient temp is down and engine is normal temp, less likely to have vapor lock. Crawling creates the worst condition for all of these.