Off idle bog - previously running well, '74 D-Jet FI Options

[Nogoodwithusernames]

Hey guys, so after replacing all my fuel lines and vacuum lines everything was going great until the fuel tank settled down a bit and pinched the return line somehow causing excessive fuel pressure and popping a line off. Been a while since that but finally got new lines (again) under the tank (I even went stainless braided to help avoid kinks and such) but now I have a major bog as soon as I come off idle. Idle does wander a bit between 1000 and 1500 so I'm thinking vacuum leak but I didn't have any problems previously until finally starting the motor again after re-redoing the front fuel lines.

All vacuum lines are connected, aka no loose vacuum hoses anywhere. Fuel is right at 28 or 29PSI.

This is all on a 2l D-Jet system.

[boxsterfan]

Hey guys, so after replacing all my fuel lines and vacuum lines everything was going great until the fuel tank settled down a bit and pinched the return line somehow causing excessive fuel pressure and popping a line off. Been a while since that but finally got new lines (again) under the tank (I even went stainless braided to help avoid kinks and such) but now I have a major bog as soon as I come off idle. Idle does wander a bit between 1000 and 1500 so I'm thinking vacuum leak but I didn't have any problems previously until finally starting the motor again after re-redoing the front fuel lines.

All vacuum lines are connected, aka no loose vacuum hoses anywhere. Fuel is right at 28 or 29PSI.

This is all on a 2l D-Jet system.

Possibly a worn TPS board? Could be leaks in the components (MPS, AAR, decel valve, distributor vacuum advance, etc...).

Everything about D-Jet (scroll down just a bit).
http://members.rennlist.com/pbanders/


Perhaps just triple check all your vacuum hoses again? The wandering idle seems to indicate leak.

[Nogoodwithusernames]

So quick question then, do I really "need" the decel valve hooked up all the way? The stacked elbow is a few weeks out still and that is definitely leaking for sure... Can I just bypass it and run the big hose straight in without having the little one hooked up right now?

[TheCabinetmaker]

Take the decel out and cap the connections. It will run without it.

[boxsterfan]

"All vacuum lines are connected, aka no loose vacuum hoses anywhere."

AND

"The stacked elbow is a few weeks out still and that is definitely leaking for sure..."

are not congruent.

"con·gru·ent
kənˈɡro͞oənt,ˈkäNGɡro͞oənt/
adjective
adjective: congruent

1.in agreement or harmony."

[TheCabinetmaker]

Ha! I should have caught that. Ou?

[Rand]

You installed stainless braided fuel lines to avoid kinks instead of routing them correctly? Because a pinched return line blew a fuel line off? What kind of clamps do you use? Please show us a pic of your fuel pressure gauge setup.

[Nogoodwithusernames]

"All vacuum lines are connected, aka no loose vacuum hoses anywhere."

AND

"The stacked elbow is a few weeks out still and that is definitely leaking for sure..."

are not congruent.

"con·gru·ent
kənˈɡro͞oənt,ˈkäNGɡro͞oənt/
adjective
adjective: congruent

1.in agreement or harmony."

Nah they are perfectly congruent since the second post is after doing some more checks, realizing it was leaking after disconnecting it and sticking my finger over the port in the plenum and having everything even out. Leak didn't have anything to do with loose hoses anyways (IMG:style_emoticons/default/biggrin.gif)

They are routed correctly, in the exact same place they were stock. I tried different lengths of normal fuel line under there and I couldn't get good results, so I went with an upgraded material that has so far solved the issue.

Clamps are all FI clamps not worm clamps.

Gauge was hooked up on the driver side fuel rail after disconnecting the cold start valve. Don't have a pic cause it's pretty simple. Same setup basically as was on my Squareback's D-jet.

[boxsterfan]

"All vacuum lines are connected, aka no loose vacuum hoses anywhere."

AND

"The stacked elbow is a few weeks out still and that is definitely leaking for sure..."

are not congruent.

"con·gru·ent
kənˈɡro͞oənt,ˈkäNGɡro͞oənt/
adjective
adjective: congruent

1.in agreement or harmony."

Nah they are perfectly congruent since the second post is after doing some more checks, realizing it was leaking after disconnecting it and sticking my finger over the port in the plenum and having everything even out. Leak didn't have anything to do with loose hoses anyways (IMG:style_emoticons/default/biggrin.gif)

They are routed correctly, in the exact same place they were stock. I tried different lengths of normal fuel line under there and I couldn't get good results, so I went with an upgraded material that has so far solved the issue.

Clamps are all FI clamps not worm clamps.

Gauge was hooked up on the driver side fuel rail after disconnecting the cold start valve. Don't have a pic cause it's pretty simple. Same setup basically as was on my Squareback's D-jet.

Sounds like you got it all figured out.

[Nogoodwithusernames]

Yep, thanks guys for the suggestions and confirming my suspicions of vacuum leak.

[Rand]

Odd. Has anyone else seen a vacuum leak cause a DJet to bog? I've had it cause high idle, but never bog. Doesn't compute.

[TheCabinetmaker]

Vacuum leak =high idle. Makes off idle better in my experience but what do i know?

[Nogoodwithusernames]

Odd. Has anyone else seen a vacuum leak cause a DJet to bog? I've had it cause high idle, but never bog. Doesn't compute.

Not sure, but before I pulled off the stacked elbow I could slowly open the throttle and it would bog and almost die (If I pulled quickly to WOT it would do just fine though) Don't know if it was too lean from the leak or if the D-jet corrected it to overly rich. Now that it's sorted, until the new rubber elbow comes in, it seems like it's running properly.

[Nogoodwithusernames]

Just an update on this, got the stacked elbow in and got it installed and it solved the previous issue. Thinking I just need to do a general tune-up though as I'm still having a couple small running issues. Won't stay running at idle unless I play with the throttle, I'll start with valves and timing, see if I can find any other leaks in the vacuum system that may be playing with me.
I did inspect the TPS and it looked pretty good still.

Not super impressed with the quality of it so maybe if 914 rubber wanted to make one I'd be down to buy one. Didn't see it on the website when I was looking for it.

I need more hours in a weekend so I can have time to still mess with the 914 after everything else, but hey at least it's not up on jack stands! (IMG:style_emoticons/default/lol3.gif)