1997 5.7 Volvo/Omc SX set uo with TBI runs cold, closed loop???

[diverpat]

Hello all, I just bought a 1997 Seaswirl Striper 2600 WA with the 5.7 Volvo/Omc SX set with TBI, engine was rebuilt 1/14/2013 with about 100hrs on it per previous owner and has sat for a few months due to he and sevearl of his friends went in and bought a 40ft boat. I took it to the harbor and ran the engine, it only got to 120 degrees, my question is does it stay in a closed loop condiotion like a car does, does it affect timming as well as other performance functions, Iv'e never owned a TBI set up before. It idles ok but going off idle it trys to quit and sometimes back fires thru tbi, I can throttle thru it but it revs up pretty high, making it difficult to operate in the harbor, plus I want it running correctly. I'm going to change plugs and wires, reset timming and clean TBI, will also check to see if I have a thermostat and buy one if I don't, will probably replace the one I have just incase, any info on this will help alot, thnx

 

[ericga]

Re: 1997 5.7 Volvo/Omc SX set uo with TBI runs cold, closed loop???

Yes closed by a 160 thermostat. Running cool cause an EFI engine to run rich, but not to the point of trying to quit and backfire.

Are the plugs black on one side and not on the other? You may have a clogged or faulty injector. Chances are your engine is affected by the famous fuel pump inside paint issue which clog fuel strainers, pressure regulator and injectors.

Your TBI should be a marine version of the Rochester TBI220 which was often found in GM trucks from 89-95. These TBI are fairly simple and easy to work with.

 

[BRICH1260]

Re: 1997 5.7 Volvo/Omc SX set uo with TBI runs cold, closed loop???

Sounds like the underheating problem is a result of a clogged thermostat housing bypass passage. Check it for debris, such as small pieces of rubber impeller.

 

[Tail_Gunner]

Re: 1997 5.7 Volvo/Omc SX set uo with TBI runs cold, closed loop???

Under 140 degree's there is a enrichment cycle above that it clears up. You may want to take a neon light and watch your injectors pulse,they should have a nice concial spray pattern no drip's. If they drip have them professionally cleaned.

There open loop speed density