89 mid cabin fuel consumption

[mrrudely]

hope someone can shed some light

both engines have had recent valve jobs 454 crusaders
rebuilt quadrajets
new fuel pumps 8psi dead head
new plugs, wires, coils
racor fuel filters
starboard has new pertronix ignition module

problem-
port engine is not burning all fuel at start up
dumps fuel into the water (alot)
old plugs were black
according to floscans port reads 8 -12 gph cold, starboard reads 4gph
after significant warm up port reads 3, starboard under 2 (idle at dock)
underway at 1200rpm both are at 3gph
at 1800 both at 6gph at 3000 both at 18gph
anywhere in between and above 3000 port uses 10 - 20% more fuel

carburetors have been swapped so its not the carburetors
I don't think it's the choke, I have held it open manually no help
floscans have not been calibrated but have also been swapped (besides there's a ton of fuel in the water)
port distributor (prestolite 7801B) is missing one spring I plan on temporarily taking spring from starboard to test

any thoughts?
a big thank you in advance
rr

[prowlersfish]

Fuel pressure is high 4-5 psi is where you want to be. Just to start check the timing be sure the tachs are right. 10% difference is not abnormal

[BobCT]

I know you ruled out choke but for reference, I manually disabled mine and I'm in the northeast. I never noticed any difference in cold starting. My Q-jets were tuned perfectly though so maybe that wouldn't be an option for you right now. I have years of video on my mid cabin showing the flo-scan data, speed, etc.

Can you swap fuel pumps? Mine were mechanical so I don't have any firsthand experience with the 454's and electric fuel pump. Is 8psi on both engines?
The missing advance spring will make a huge difference especially around 3,000 RPM range (+/-).

Bob

[mrrudely]

thanks guys

fuel pressure on both (mechanical pumps) is deadhead 8psi
agreed that this is a little high but not enough to push through the needle valve
also reading is equal on both engines while problem is only with port engine
port engine is putting gas in the water at start up, can't see this as a tachometer issue
there is significant improvement when it reaches running temp (but not 100%)
I plan on borrowing the missing spring from the stbd engine but I don't think that's it
I have attached the results of the most recent sea trial
there may be a leak down test in my future

rr

Screen Shot 2022-02-02 at 10.47.25 AM.png (75.91 KiB) Viewed 13172 times

[prowlersfish]

Check your timing with and without the missing spring. You say you swap carbs with the same results? Is your fuel burn difference conferred when you fill-up? Fuel on the water only at idle speed? The thing I find odd is the big difference at some rpm and a match at others. Let us know what happens with the spring.

[mrrudely]

I was not able to access the spring I needed from the stbd engine (so I could try it on the port side)
I have a feeling the one spring that is in the port side is weak as well as one is missing
I am beginning to think these springs are part if not all of the problem
The distributor is discontinued and I have so far been unable to find the springs
I am not in a hurry to take the distributor to a shop
If I need to take it out I will probably just replace it (Delco $500.00 ouch!)

carbs were swapped, stbd engine runs fine with either carb

floscans have not been calibrated but they are not needed to see the issue (excessive fuel burn at start up as high as 8- 12gph when cold)

I am thinking the difference in fuel consumption during the sea trial could be the missing spring as that could effect the timing curve

checking the timing is high on the list certainly before compression or leakdown test

thx

rr

[RWS]

check timing with an ADVANCE timing light on both engines to confirm correct operation of advance.

RWS

[mrrudely]

mystery solved!

I had previously attempted to remove the carburetor at least once without disconnecting the choke coil.
I apparently stretched the coil so it would keep the choke tightly closed.
After a very long warm up period it would open but the harm was done, I had fouled plugs.
I have disconnected the choke entirely while I look for a replacement.

I now think the distributor had nothing to do with the problem but I replaced it anyway because of the missing advance spring issue and age.
I will discuss that installation in a separate post.

rr

[Moderator]

Thank you for the update.

[mrrudely]

I removed the choke coil from the port engine
and removed the choke coil cover from the starboard engine
it seems as if it was the starboard choke coil is the one that I may have stretched out (not the port) thereby keeping the choke
somewhat open when cold

so my explanation was not accurate
however I still believe the problem was a tightly closed choke (on the port engine the problem one)

so my question is where would that condition come from
and how can I best correct it?

rr

[prowlersfish]

You can try replacing the choke coils or adjusting them. I have always hated chokes on a boat. over the years I set some very loose, and disconnected some. Just need to warm up the boat a bit before going out. Do you have a photo of what choke style you have?

[mrrudely]

I am attaching a photo of the stretched out starboard choke coil
and the wound tight port choke coil
The starboard coil binds up in its housing
I have not been able to get it off yet
I hope to straighten in out
I am thinking of lengthening the linkage on the port side so it will start out leaner
thx
rr

[prowlersfish]

https://www.ebay.com/itm/372929137371?f ... SwKfBhDSsJ

[mrrudely]

there seems to be left and right versions of those choke coils
also crusader has two part numbers listed, one for 0 angle and one for 12 degree down angle according to a post I found on another forum
today I started both engines without the chokes
no problem
that's the solution for now
thanks everyone
rr