I've got a 1999 V6 3.0 (flex fuel, if it matters) and I'm in the process of taking off the upper manifold so I can access the fuel injectors. (I'm trying to take care of a P0305 code -- cylinder 5 misfire.) I've crossed out the coil pack, spark plugs, so it's onto the fuel injectors.

Anyway, I replaced the whole engine about 1.5 years ago and I haven't had any problems with this area of my truck. After taking off the coil pack earlier today, I realized that there wasn't anything connected to the fuel injector damper; alternatively, it's called fuel pressure damper, fuel damper assembly. This is my first vehicle and it's been a journey learning about the mechanics of cars, etc. hence me not realizing that there wasn't anything connected to the damper when I first replaced the engine until now. This is throwing me for a loop.

What is supposed to be connected to the outlet on this fuel injector damper? Is there supposed to be a vacuum hose connected to it? If so, where does this vacuum hose lead to? Or is just a ventilation hole and there isn't anything connected to it?





Thanks for any of your help ahead of time.

 

Its a Safety Vacuum hose, hooks to upper intake vacuum source.

If the Damper's diaphragm should start to leak, gasoline would come out that port, and drip onto a hot engine, probably not a good out come for that, lol.

So they added the vacuum hose in case of a leak, it isn't a "active" vacuum device, hose is there for safety reasons.
So I would hook it back up, or "T" to another vacuum hose if you can't find an open port on the intake.


Did you check compression?
Outside of swapping spark plugs and wires for #5, that would be the first place to start
Compression is black and white, good or bad
If it is a compression issue then a waste of time and money looking at spark or fuel
If it isn't a compression issue then you know it is spark or fuel so not wasting time and money on those

 

Hey RonD, thanks for the quick reply.

I did check compression on #5, and it came in at 145 PSI. I'll have to look tomorrow for a vacuum intake that isn't being used. If not, I will follow your advice and "T" the damper into another hose. It would have to be a vacuum hose connected to the upper intake, correct? Tomorrow I am going to pull the fuel injector from #5 and test it.

 

The main vacuum port is at the back of the upper intake manifold, pointed out in purple.
If you remove the vacuum line from that area that leads to the brake booster, you can see it better.

The green arrow looks like the line there that goes to the dampener.
The blue arrow points to what looks like masking tape blocking it off.
There's an elbow that looks like it's missing where the masking tape is that would other wise lead to the dampener.

And if you're going to "T" it, use one of the red vacuum lines, but I'm pretty sure that the one pointed out in green is the one used for the dampener.

 

145psi is fairly low, 3.0l runs 9.3:1 ratio so 165psi is expected

If you tested at least 2 other cylinders and they were 140-150psi then 145 would be OK just compression gauge or crank speed fault
Or you live above 2,000ft elevation

 

Thanks, Jeff R 1, for the reference pic. It really helped out. I did end up finding the vacuum hose's connection. It must have got knocked off when I was changing the spark plug hoses or something (because I still swear up and down that I connected it when I put the engine back together after replacing the engine block).

RonD,
Hmm, duly noted. I did check the other cylinders on the driver's side (4 & 6), and they both came out at 145 as well.