[Zook101]

Hi there,

Chasing some help on my 1987 Suzuki Sierra, Wont Idle Smooth, When its cold Sits at 1000RPM Is Great Soon as it gets up to Temp Irratic and surges Between 1000RPM and 1500RPM drives fine has plenty of power soon as you put the Clutch in while driving stalls replaced all vaccum hoses checked the choke working fine swapped over EGR valve still nothing, Tested Compression 150 Over all Four Cylinders Tryed adjusting the timing Advanced 5DEG and 20 Deg before Still no good, Replaced fuel filter drained tank Pulled the plugs out All good besides Last plug closest to the Firewall Was black the rest were white. Does this Mean Valve clearenece issue???

[zukmeista]

Black plug means running rich, not a valve issue. Could be a stuffed plug, so considering how cheap they are slap a new set in it and see what happens. Or if your a tightass like most suzuki owners, put one of the normal plugs in that cylinder and see if it goes black. And the plugs shouldn't be white, should be more of a grey colour.

[Zook101]

Thanks for the Reply,

They are a new set but i might go buy a new one tonight and try that, What does white plug mean too hot??

[HellonWheels]

Had the same problem recently aswell. Could possibly be the idle jet in the carby. Try swapping no 2 and 3 leads to make it backfire(Remove aircleaner assembly first) or try to rev it up and cover the intake with your hand untill it almost stalls.

[Zook101]

Hellonwheels, Thanks for that might try that are they the middle two Leads??

[HellonWheels]

yep swap 2 and 3 and rev it so it backfires, might be a clogged idle jet.

[zukmeista]

Zook101 wrote:

Thanks for the Reply,

They are a new set but i might go buy a new one tonight and try that, What does white plug mean too hot??

What plugs are you using, should be NGK BP5ES I think.

[HellonWheels]

Im just playing with plugs aswell, ive tried BP5ES, now running BP6ES. either will work,just make sure to check the gap on them before fitting.

[zukmeista]

No, BP6ES are too hot for a G13, BP5ES are the right ones.

[jono165]

Bp6es is fine. It's what I run and several catalogue a reccommend them or equivalent. Fuel has changed in 20 years or so but either plug will work fine.
Also a bp6es is a cooler plug than a bp5es

[zukmeista]

Whatever, the standard recommended plug is a BP5ES.

[Zook101]

I've got BP5ES Changed out the Plug last Night No Good, Swapped the leads over backfired a few times, Still no good ripped the carby off for the second time Pulled out the Lower Jets One seemed Dirty than the Other Cleaned Both Put Back Together Test run at 10.30PM Ran @ 800RPM didnt play up. I will be trying again tonight but hopefully all Fixed thanks fot the Help Guys. Thank you Thank you

[zukmeista]

Cool, to prevent further problems install an inline fuel filter between fuel pump and carby, stops shit from the fuel pump getting to the carby.

[Zook101]

No worries Zukmeista Ill Get One Tonight.