My 89 rx7 vert na just started running like it wasnt getting enough gas then it would Its got a new walbro 190 fuel pump ,screen, fuel filter and fresh clean tank It had a motor rebuild 10,000 mi ago Its been running fine till the otherday when In 5th gear under 4k it will act like the fuels being restricted then jump back up to normal But when i put it in 4th gear and keep it over 4k it runs fine Also here lately it takes longer to start than it used to I cant find any threads out there that like this that can help Maybe someone out there can help me

 

so is it "bucking" under 4k rpms? and only in 5th gear?

 

no just like losing a little power then comming back up again but if i shift it to 4th and the rpm goes over 4k it dosent do it This is whin im on the interstate

 

Not sure how many different pumps are made by Walbro, but some would tend to say that a Walbro is a bit too much for an NA and they are designed to raise the fuel requirements necessary for turbos.

 

that sucks This walbro 190 lph was said to be a replacement for rx7 89-95and that if the car was turbocharged or supercharged you should upgrade to the 255lph its been running great for 3 months since i put it in now i dont know what to think or do

 

check grounds.

 

What series car and how is the pump wired?

 

If the pump was designed for that particular series then it's likely not the problem itself, but caused more likely due to wiring.

 

Bit left field but how's your clutch

 

i believe its 13b s5 fc the vin is JM1FC3515K0700667 Its wired the same as the old one

 

the clutch seems fine I jumper the interlock switch because it was bad

 

its getting 12v and wired the same as the old one and pumping the proper pressure what else should i check

 

Well as someone stated earlier you need to check your grounds. And perhaps your problem 'might' be caused by your 5th and 6th ports not actuating properly.

 

have check the grounds for a few month every thing seems to be ok will check tho ports

 

And your exhaust could also be playing a role.

 

By the way i forgot to tell you it been backfirlng (not real loud) when i rev it

 

like what has a new exhaust(1year ago)

 

I was referring to the catalytic converters.