Fuel/Carb help needed

[C_I_A03]

Ok, so I've been driving for the past few weeks and I'm tired of my GW stopping on me when I come to stops. As I slow down it seems as though the engine does as well, but it doesn't stop at a certain RPM, it continues to slow down till it just dies. I can shift into neutral, give it some gas (light feathering) and it'll stay fine. I can then shift into drive and go, however when I have to break fast, I don't want to shift into N b/c if I miss and go into reverse, I'm in real doo doo then.

Now when starting I'm sure its just b/c the engine is cold, however the engine, once started, revs high, settles down (like it should) but then slows down to a very low RPM. If I'm careful, ie little bit of gas, it'll stay running and I can then leave it, however not for long w/ out giving it gas.

If anyone knows what I need to do, please help. I don't know much about carbs and how to tune them, but I have a new one, new spark plugs and wires, and a few new hoses as well. OH there is also a heavy gas smell as though it's running REALLY rich, or not burning everything (which would be why I'm only getting 6-7MPG)

TIA

P.S. Shouldn't this --> be bigger, or more properly shaped?

[shimniok]

What year of FSJ? What type of carb, 2v or 4v?

If it is a 2100 carb or 2150 your power valve is probably shot -- common -- and causing it to run way too rich at idle/cruise.

Could also be a stuck choke causing it to run rich. Indicator of this would be that it does ok when it is cold and gets worse when warm.

Otherwise it might be in need of idle mix adjustment but I'd rule out the other two before trying that.

Michael

[C_I_A03]

It's an 88 w/ 360 2bbl 2150. As for the power valve, would it go that quickly? I've only had this carb on there for >3K miles. The stuck choke sounds like it could be the culprit because recently in the AM when I head into work early the engine runs ok. I'll have to test that. If it is a stuck choke valve, how do I go about fixing it?

Stephen

[shimniok]

It's an 88 w/ 360 2bbl 2150. As for the power valve, would it go that quickly? I've only had this carb on there for >3K miles. The stuck choke sounds like it could be the culprit because recently in the AM when I head into work early the engine runs ok. I'll have to test that. If it is a stuck choke valve, how do I go about fixing it?

Stephen

Start w/ choke as it is easiest to check. Wait for warmup. When warm, remove air cleaner housing lid, observe choke valve on top. If open (pointing up/down/vertical) ok. If closed, not ok. If that is the case check electrical connection to choke and ensure voltage is getting to choke when engine is running. That is most likely cause. Let us know...

Michael

[C_I_A03]

It's open when warm, infact it seems to always be open, though i haven't let the engine sit for more than 6 hours at any time w/ out running so it might not be enough to let it cool. I'm going out of town today so I'll check that it closes in the AM when I start it, but it is open (up and down) when warm.

[shimniok]

It's open when warm, infact it seems to always be open, though i haven't let the engine sit for more than 6 hours at any time w/ out running so it might not be enough to let it cool. I'm going out of town today so I'll check that it closes in the AM when I start it, but it is open (up and down) when warm.

I assume it is running rich. Rich would tend to cause lower power, bog, and slowly recover after hitting gas, bad mileage. Lean usually manifests as motor nearly dying out when hitting gas... like temporary 'flame out' and it catches and goes; also, low power, surging at cruise. You can check plugs. White plugs = lean, black plugs = rich.

So since it isn't choke, it might be power valve. The pv is in the middle bottom of carb, usu there is a hose fitting that a vac hose is attached to.

Make sure the hose connects to a good solid manifold vacuum source. Otherwise it will run super rich at idle and cruise.

Check to see if gas is leaking out of the vacuum hose that runs to the middle bottom of the carb. That is definite sign of power valve bad. But they also go bad without leaking.

If no leak on power valve, you can try playing with idle mixture. Screws should be around 2 turns out give or take 1/2. If adjusting idle mix doesn't help at all, that suggests power valve is dumping fuel. Another thing you can try is to see if you can get it set to lean idle to where rpm is a bit lower than at best idle. In theory if you pull the vacuum source for the p.v. it "should" increase the idle because pv opens and makes it run richer. If nothing happens, to me that is another indicator of power valve bad.

I'd think about replacing the power valve & rebuild the carb while at it (rebuild kit will have p.v.).

hope this helps

Michael

[JamesM]

Edelbrock is the answer

Have you noticed gasoline leaking (literally!) out of your exhaust system? Princess did that a few years ago when the power valve ruptured. Even when fixed, she would tend to die when you tried to pull out into fast, moderate traffic - especially when turning left into traffic! After one minor accident and two near-T-bone close calls, I ripped that piece of junk rebuilt carb off, returned it to AutoZone, and pointed to the brand spanking new Edelbrock 1406 (4BBL) carb on the shelf and bought it for about $30 more than my refund. Of course we had to install the intake for it. Bottom line: Princess runs great, now. She doesn't die AND she got roughly a 2 mpg boost -- despite the thrill of opening the secondaries!

One word of warning: I did not see an Edelbrock intake that accepts all the stock anti-smog stuff on an '89 GW - so I'm cutting smog by running better rather than using all that old-tech plumbing.

Hope this helps,

-James

[shimniok]

One word of warning: I did not see an Edelbrock intake that accepts all the stock anti-smog stuff on an '89 GW - so I'm cutting smog by running better rather than using all that old-tech plumbing.

My edel manifold accepts all the 86 smog stuff. I don't think 88 is adds anything... since there's nothing else to add. No other emissions devices exist aren't already on the 80's FSJs. So, mine had fittings to support EGR, AIR, TAC, all the CTOs (3 of them), PCV, NLVR, etc.

If you ask me, from an emissions point of view I think the three critical items are EGR, AIR, and cat. The EGR lowers combustion temps to keep NOx in check. The AIR system burns up any excess HCs in the manifolds or cat and takes little power unless the pump is going bad. It just looks ugly and takes up room.

Michael

[C_I_A03]

Well the PO already took off the AIR and a bit of the other smog stuff. I'm not fully sure what else has been removed but I know the AIR and one of the CTO's aren't getting anything from the carb. However all this stuff started happening recently so i really don't think that the lack of these is causing it. I'll start up and see if I have gas leaking out the pipes and the hoses. I'll check also the fuel mixture and the hose to the manifold before i start rebuilding the carb/replacing it. IF it does come down to replacing it, how much would a new intake be in addition to the carb? OR what vehicle could i rob to get it? Thanks for the help.

Stephen

[Wayne]

Could be the float,or the fuel inlet
valve is in bad shape, letting to much
fuel in.

[moorehouse77]

Yeah I had pretty much the same thing on my '77. It wouldn't quite die but it was real close and the mileage was really bad. It turned out to be a small sliver of metal from the fuel fitting that had stuck itself into the rubber at the tip of the fuel inlet valve on the secondary bowl. It didn't happen for about 6 months after I put my Holley on, even bouncing around off road. Just one morning it did it. If all else fails take a look. Good Luck?!!!

[C_I_A03]

So I just cleaned up (best as one can from 20 years of engine grim) and found that the hose from the manifold to the PV came undone at the manifold valve. I scrounged up some new hose, rerouted it (so it wasn't being stretched) and away I went. It seemd to lug a bit at stop, but the engine kept going. It could be at this point that I'm low on gas and need some more for the 360 to guzzle. Thanks for the help all.

[shimniok]

IF it does come down to replacing it, how much would a new intake be in addition to the carb? OR what vehicle could i rob to get it?

If at some point in the future you wanted to swap to an Edelbrock you could use a square bore AMC manifold from FSJ with Motorcraft 4300 ie ~ mid 70's (74, 75 ... not sure what other years... this is pre-motorcraft 4350). You can also adapt a Qjet to fit a square bore. Otherwise you can watch eBay for Edel performers or Offy 360's.

Michael