1988 Dodge Raider 2.6L

[chio916]

Hello fellow members,
I really need help with a carb issue or fuel related problem. I got the carb replace couple weeks back.
I,ve replace the ignition coil, spark plug and the o2 sensor, replace fuel filter. timing adjusted to stock setting.

- When i start the vehicle up, it starts and revs fine. but when i take it out for a drive and fully step on the gas pedal, the engine boggs down (lack of power) if i slowly rev up while driving, it does the same thing at around 3k rpm. There was one time the float got stuck and flooded, i drove it around with full power. any help is greatly appreciated.

thank you

[xboxrox]

Hello chio916 FUEL PUMP replace that sucker ? I dunno how to test it but I am experienced in throwing parts :thumbup: where you get a replacement carb? Mikuni original carb?

GOOD LUCK MAN -- my hometown Sacto

[FMS88]

Welcome to the site. Did you replace the carb yourself or have a shop do it? If the latter, take it back and have them diagnose the problem. They can also check the fuel pump pressure to see if that could be the issue if the carb isn't the problem.

[chio916]

I’ve replace the carb myself, pretty straight forward. Got the carburetor from national carburetor. Should I just do an electronic fuel pump conversion? Or just replace stock pump.

thanks.

[geezer101]

If you have the stock carb, the mechanical fuel pump is fine. Are the secondaries opening? This sounds a lot like a dead secondary vac actuator - no power under throttle and nothing from midrange upwards. If the diaphragm in it is split, it won't open the secondary throat and will also create a vac leak. Remove the air filter, disconnect the small elbow vacuum hose on the secondary solenoid and attach a longer hose to the solenoid, then suck on the other end of the hose. If you can pull air through it continuously, it has failed. It can be replaced without removing the carb but it takes a bit of manipulation.

I don't 'think' it's the fuel pump - it would drive fine until you got it onto open throttle and then it would struggle. I don't think it's a distributor fault but it could also have a bad vac advance (use the same method as the secondary fault diagnosis) which would nerf ignition advance (subsequent lack of power but would still have full rev range).

[chio916]

If you have the stock carb, the mechanical fuel pump is fine. Are the secondaries opening? This sounds a lot like a dead secondary vac actuator - no power under throttle and nothing from midrange upwards. If the diaphragm in it is split, it won't open the secondary throat and will also create a vac leak. Remove the air filter, disconnect the small elbow vacuum hose on the secondary solenoid and attach a longer hose to the solenoid, then suck on the other end of the hose. If you can pull air through it continuously, it has failed. It can be replaced without removing the carb but it takes a bit of manipulation.

I don't 'think' it's the fuel pump - it would drive fine until you got it onto open throttle and then it would struggle. I don't think it's a distributor fault but it could also have a bad vac advance (use the same method as the secondary fault diagnosis) which would nerf ignition advance (subsequent lack of power but would still have full rev range).

would you happen to have a picture of the secondary? I’m a little lost with this.

thank you for your help

[chio916]

Would you happen to have a picture of the secondary? I’m a little lost with this.

thank you.

[geezer101]

It's the big round component attached to the throttle linkage side of the carb (it has a 10mm flare nut holding it onto it's mounting bracket) There is a small rod that passes out underneath it - this actuator rod is connected to the end of the secondary throttle shaft. The secondary shaft is locked closed when the primary isn't open so to do this test and ensure it's working, you need to fully open the primary by turning the throttle linkage by hand and then drawing vacuum on the test hose. You should see the secondary pull open when vacuum is applied (tried to find an image on the site but it was taking forever...)

[camoit]

It sounds like the acceleration pump in the carb is not working or it needs more advance on the distributer.

[xboxrox]

Yes to all these suggestions... chio, do you know the maintenance history of your ride..? How many miles on the clock (?); when if ever was the fuel pump replaced..? My truck has 133,000 miles and had similar problem; after replacing the fuel pump, it ran better... Timing was adjusted more advanced by a local mechanic and it ran better... You can look down into the carburetor (engine off) and see gas squirt when the throttle is opened, meaning the accelerator pump is most likely ok... Do geezers test to ensure the second throttle plate opens but it seems your ride has trouble running even before they open... Assuming the carburetor you bought is good, you do need to make sure enuff fuel is reaching the carb... Have you replaced the fuel filter ever..?

Thanks for asking for our help :thumbup:

P.S. For proper torque, when you bolted on the new carb, did you clean & use lithium grease on the bolt threads (?) how well did you clean the intake manifold to carb gasket seating surfaces..? Any leaks, even small ones will cause plenty trouble... I used Seafoam gas tank treatment and the truck ran better...

Have you followed any carb adjustment instructions from National Carburetor FSM or a Haynes Manual..?

[chio916]

Thanks guys for all the suggestions, so I’ve done some diggin around and realized that with the air filter cap on, it bogs under load. I remove the air filter and close and cap, same problem. But with the cap completely off. It drives fine. The duct is not clogged. What you guys think the problem is? Seems to be starving for air or gas.

[FMS88]

Check the choke. With a hot engine, is the butterfly valve completely open? Also, after driving a while and experiencing the symptoms, remove and check the spark plugs. If black and sooty, it's running rich; white and it's running lean.
If the choke opens and it's rich, perform the quick test of the bowl vent valve on pages 13-14 described in this guide:

[chio916]

Just went in for smog, smog guy failed me on dyno stating my carb is dumping a lot of fuel. I got new o2 sensor on it aswell

[geezer101]

I'm going to say something here that might not go down well but there is a chance they did a dud rebuild. If it's assembled correctly it should be in the ball park for tuning/running straight out of the box so to speak. Might be an improperly set fuel bowl float needle and seat. It shouldn't be able to dump fuel. If the choke is set wrong it will only run rich. And is your fuel pump a dual outlet? Make sure you have the fuel hoses orientation correct. Normally crossed hoses will result in inadequate fuel supply to the fuel bowl so IDT this is the issue. Looked up National Carbs and they have mixed reviews (my bet is their main ticket is 4BBLS, old 2BBL classic car carbs and singles for VW etc)

[FMS88]

I agree that the rebuilt carb is defective and should be returned if still under warranty. My suspicion is that the bowl vent valve has failed and it is causing the rich condition. The attachment below describes the condition and the fix. It even mentions what you found, that removal of the air cleaner decreased the rich condition.

24982

Don't try to fix it yourself. Full access to the valve requires removal of the top of the carb; not a simple task and it would void any warranty.

[chio916]

Im going to call nation carburetor tomorrow, get a new ticket for warranty exchange. Fuel fuel pump hose fitting, seems to be right off the diagram. I’ll let you guys know once they exchange my carb. Thank you

[geezer101]

Good luck, hope you get some resolution from the vendor.