1988 BB Detroit Deisel 8V92 Wont Start

[Crabber82]

Attention all Gurus,
My 1988 BB WL with the Detroit Diesel 8V92 is failing to "FIRE". Started last week to go on a week long outing and when I tried to come home she failed to start. It was a very expensive tow back to Katy, Texas.

So here is the skinny:
Good strong Batteries
engine cranks, good starter
fluid levels all at operating levels. Oil just replaced. oil filter replaced.
Fuel filters both Racor and Secondary replaced, filled and oiled seals
Yes, the A/T switch is detente to the left or run position.
Master battery switch in "on" position

Fuel lines have been checked and "bled" from fuel tank to fuel pump.
Yes, there is fuel on board fresh and new.
Generator is running so fuel confirmed in tank.

all this said, My Bird is failing to fire and I am perplexed. If anyone can point me in the right direction I will be happy to try. Two diesel mechanics visited the site and both tried exactly the same stuff I did...

Gas rag in air filter tickled the ignition but failed to keep it running. Starter fluid (in small doses) spurred the same result.

manual primer button pumped to a rigid firmness turns into a marshmallow after key turned.

Has anyone experienced a like incident?

[Gregg]

My 8v92 loves to be warm, I assume you have used the engine heater.
Also, there are three relays below my oil fill, passenger side, check them. They are known to be start killers.

[mbulriss]

Bummer. We all feel your pain. I haven’t seen a Bird towed that way before, but I guess “why not?” if it works.

I only had start problems about three times in almost 20 years of 6V and 8V ownership. Most notably the AT switch got hit. I would cycle it and try it on both sides. I know you checked it but I’d still try it. The second time was a bad spin on fuel filter. I opened it after trying to start and it was only half full. Put another fresh one on pre-filled with fuel and started. The final issue was ground straps from engine to frame. My son says on his OTR trucks when they don’t want to fire up “it’s the ground, it’s the ground, it’s always the ground”. That may be a little overstatement but those 6V/8V DD do like a good ground. You need to crawl under and should find several ground straps from block to frame. Pull them off and wire brush the cable ends, block/frame mounting points and the retaining bolts. Lot of folks have added additional ground straps for this kind of reason. I assume you may have already done the battery cables and all their connections to the starter and frame. I will also assume the DDEC box and connectors are clean.

Also, just out of curiosity, did you try starting it from the engine compartment control box? Hopefully, it won’t be something obscure, like a bad oil pressure sending unit.

Good luck and let us know what the end result was.

[Crabber82]

Hi Gregg
Will look for these relays below the "oil Fill" tomorrow.

---

Hi Mike,
Have been all up under checking and cleaning ground straps. Yes, battery terminals and cables are clean and shiny.

Have experimented with attempted starts from both the drivers seat start switch and the engine bay start switch. The engine bay switch is a blessing by the way considering the number of trips back and forth one would have to make. Also the opportunity to be standing at the engine to here what is going on.

The A/T switch performs exactly as advertised. Detente left, engine turns over. Detente right, engine/starter does nothing. So I have ruled out the A/T switch.

As for the tow, Yeah...that alone was a nightmare. Four different companies walked away from even attempting but Tyler at BDS Recovery in Texas told me over the phone it would be done. 5 hours later it was done. Huge relief for me and high praise for Tyler and BDS.

[mbulriss]

Just sitting here re-reading your posts and thinking to myself gas internal combustion engine needs fuel/fire/air; diesel compression based engine just fuel and air. If I read your post right, the engine fires briefly with the gas rag and ether but doesn’t stay running. Correct? You said the lines from the fuel tank to the fuel pump were checked. Was the output side of the fuel pump pressure tested? Your comment about the manual fuel primer turning soft immediately after turning engine over got me to wondering if the fuel pump is providing proper pressure. Did the mechanics check that?

As a reference, I recently went through a similar problem on the Kubota gen set engine. I know the little electric pump on the Powertech gen set immediately is pressurized when power is applied but falls off immediately when power is cut but I wouldn’t think the DD pump would fall off as quickly. Luckily for me, I never had to mess with fuel delivery issues on the DD outside of filters. But it got me wondering if you have fuel pressure. BTW, the gen set was a water level sensor in an expansion tank.

[Crabber82]

Morning Mike,
That is correct. With a "gas rag" or a little kick of ether it will act like it wants to fire. But as soon as the "fortified" compressed air runs out...The big ole diesel just cranks.

[mbulriss]

Fuel delivery problem. Check for pressure out of fuel pump before anything else.

[patticake]

On the block that your fuel filter screws into there is square lug. Remove that and screw a fuel pressure gauge into that to see if you have pressure. Also, as JC mentioned, there is an oil pressure switch on the passenger side of the block down by the frame that requires 3psi to close the circuit to fire the engine. That switch has been known to fail.
I have had my coach for 13 years, 100,000 miles and have run across everything that you are experiencing.

[patticake]

Have you checked the engine computer codes?

[patticake]

Any more news on the start situation?