Brandonb_05

I'm no expert on that set up, but try disconnecting the oil pressure sensor that goes to the pcm/ecm not the gauge sensor. Once the wire is disconnected put the wire to a known good ground and see if it starts. Also try leaving the wire off not touching a ground and try to start. My sisters boat would not turn the fuel pump on until it received a signal from the oil pressure switch. Just a simple thing to try.

nunnink23

Good idea on the grounding. I have tried to start it with the oil pressure sensor disconnected, but not grounded. It didn't set any codes either while it was disconnected.

I also tried starting it with the ECT sensor disconnected, map disconnected, tps disconnected, IAT disconnected, and knock sensor disconnected.

I found it odd that it sometimes will sneeze enough to disengage the starter after siting all night, only to never start again. I thought maybe the knock sensor was detecting false knock and telling the ignition module to pull back timing immediately, but that should also send more fuel, and it's obviously not doing that.

even though I had the injectors rebuilt by CFM Tech, and then checked by my Marina, I have a strange feeling it's something tbi related. My goal this weekend is to eliminate every single other possibility, and if all else checks out okay, then it must be something TBI related. SB was kind enough to offer a known good unit to test with, so if I can't figure it out I will try that next week. I did find injectors on Rock Auto. I find it strange that they are readily available, since I was told that they are no longer in production since they are an odd pressure/flow rate.

Brandonb_05

the one I worked on would turn the fuel pump on when the wire was grounded. Made a temporary jumper wire to get home. Just make sure your checking the sender/wire for the pcm/ecm not the one that goes to the gauge on the dash. Or you can just check to see if you have voltage at the fuel pump while cranking.

BUP

Is CFM tech = SB I think I recall that in one long time thread last year.

Can I ask how your marina verified proper injector function and proper flow ?

Brandonb_05

Im curious to know what the fix will be, let us know what you find.

SB

What #'s are on top of the injectors ? If Rock Auto has them, I may have them also.

BUP - good memory. Nunn, good for you talking out loud. I never put 2 and 2 together. Boat forums are fun cause not usually related to work.

Hmmmm.All makes sense /sounds kinda familiar now.

nunnink23

Brandon,

The fuel pressure is steady 30 psi when cranking, and the pumps keep running. However I will tell you that last year, although the boat ran fine, the oil pressure sensor was disconnected. I found that out when I pulled the engine and realized the post on the sender was snapped off in the connector, and was rusted to the point that it had to have happened a long time ago. I will try grounding it. How does that sensor work? I don't remember if it has only one wire going in, and is grounded when pressure is good, and open when bad, or if it has two wires.

To be honest, I don't know how they checked my injectors. I thought CFM was a reputable place, but mistakes can happen so I sent them to my marina, who said they were flowing fine. I know these were good injectors last year, but I figured I should have 14 year old injectors cleaned while the engine was out. Now I wish I hadn't done that until I had it running again.

Do you think these injectors are actually the right ones? https://www.rockauto.com/catalog/raframecatalog.php?ck[year_1995]=true&ck[mkt_US]=true&ck[mkt_EU]=false&ck[mkt_CA]=false&ck[mkt_MX]=false&ck[viewcurrency]=USD&ck[ID]=931510976eac41fbe91225e62fb407d4&ck[idlist]=931510976eac41fbe91225e62fb407d4&ck[PHP_SESSION_ID]=2ec8qhekvqgkvvl1bj22bmon50

For some reason I am skeptical.

And I am sorry, but I didn't understand the CFM reference above lol. The closest thing I can think of is SBC.

Brandonb_05

I missed your post with the fuel pressure. If the sender is a one wire sending unit typically when oil pressure is applied it provides a ground signal. I have seen senders the other way around that would remove the ground with oil pressure but not on a boat, on generators.

nunnink23

Hahaha that's awesome. I didn't want to bug you anymore, I figured I called you enough times already in the past. I know you guys are busy, so I didn't want to send the injectors back to be checked, and my Marina offered to do it for free since they apparently have a machine.

But yes, unfortunately I have gone through just about everything I can think of, and althoigh logically it wouldn't make sense that a freshly rebuilt tbi, and injectors would be the problem, who knows. The map and IAT is the last on my list, other than taking a step back and asking myself for the hundredth time, what could I be missing.

SB

Yeh we are busy. Almost 2 weeks booked out for work.

I checked that Standard # and 2 warehouses I deal with for other things each have a pair.

Again, if you give me the GM#'s stamped on top of yours I can see if I have other one's around.

Have you tried the tap on top of injector trick ? Tap on nipple in between the posts. I had a few Holley TBI's way back that I did this too and worked...LOL.

Is the coolant temp sensor a GM one ? If so, I can look for the chart of temp vs ohm resistance and you can check to see if it's reporting right.

I have a GM tbi truck at work. Replaced intake manifold. Saw customer had new coolant temp sensor on the seat. So I installed that in new intake just because. When done. truck thru a coolant temp code and ran like crap. Barely started and died within 10 seconds or so, if it started. Redid all grounds as this is common issue on these trucks. Didn't help. Called cust to see whom's sensor, he said Autozone. Doh ! I got a Delphi and vroom, vroom.