95 volvo penta 5.8l ford wont idle (surges)

Hello, new here. I had a customer bring me his boat, its a 95 chris craft and it has a OMC COBRA 5.8L manufactured by Volvo penta model # 58faphue. it ran great last year and I winterized it for him. He dropped it off this year for me to get it ready and it would crank but it wouldn't take off. and the fuel pump wouldn't work either and had no spark. I took the spout out and it would spark then, but the fuel pump still wouldn't work. checked the kill switch system and ignition system, and figured the ECM Module was bad. changed it and it runs great but wont idle now. It idles rough and up and down, and when you come off of wide open throttle it shuts off. I replaced the MAP sensor and the Idle control valve on the throttle body, and clean the throttle body, replaced sparkplugs, checked timing with the spout out, and changed the fuel filter. I don't know where to go from here! any help would be great. I'm wondering if the new computer is bad. Thank you for any help!!

There are ECM relays on those that are known to go bad and cause intermittent problems.

Thanks for the feed back!! Do you which ones?? Thanks for any help!

I'm sorry, but I do not. It's a problem that I have read about and have in my notes in case it ever comes up for me with my 5.8l , but I have not had to research this further yet.Mine is also a 1995 FSi which would be a little different, but I do believe you would still have ECM relays located somewhere close to the ECM.

http://www.volvopentastore.com/Engi...on_id.585941146--store_id.366--view_id.792204

Not sure if it would be #60 or #81.

Also saw something recently where a bad ignition module also caused a loss of fuel and spark at the same time. There aren't too many things that will cause both to go out at the same time.

From what I have also read, ECM's themselves will hardly ever fail on their own. The ECM relay(s) can make issues appear to be ECM failures.

The Ignition modules fail, and can also be caused to repeatedly fail by the "PIP" inside the distributor failing, So if you put on a new ICM, and the new one works for a while, but does not last long, it's due to the "PIP". All of these are cheap parts. You could probably replace the 2 relays and the ICM for under $80 and be good to go.

Be sure to check back in and let us know what actually fixed this for you.

I had a similar isssue with my 5.8. Ecu was the problem. Got mine from gt40ecu.com