Can cranking the engine with no spark flood the engine?

[HarryD]

Good news. Keep chipping at it.

[doswald]

It's a process-keep at it! You are receiving excellent advice. Once you confirm spark, if necessary, move to fuel. I note from a previous post that you installed a new tank. Did you clean and flush the new tank before installation? Some of the new tanks have corrosion protection that needs to be removed before installation.

Regards,
dho

[Winter911]

Definitely got spark. Car still won’t run. Getting some nasty loud pops when cranking.
Started fluid made it pop even louder.

Could it be timing? Wet spark plugs?

[HarryD]

OK Check your timing.

This thread has lots of ideas. Before you take ANYTHING apart (besides removing #1 Sparkplug and top of distributor), just be sure you have #1 cylinder at TDC in the compression stroke and the distributor rotor is pointing at the #1 sparkplug lead.

https://forums.pelicanparts.com/porsche-911-technical-forum/637205-distributor.html

This article may also be helpful. https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/23-Timing/23-Timing.htm

[JSV798]

Are the spark plugs connected in the right order?

[Winter911]

Originally Posted by HarryD

A common problem is that the fuel lines to the MFI Filter canister are improperly routed.

Check line routing against this picture:

I’ll check timing later this afternoon, but first, I’m starting to second doubt myself on my plumbing.
I read a post where someone was experiencing the same exhaust back fires when their plumbing was mixed up.

I might have mixed up the Plumbing on the actual MFI pump.
Does this look right?
I’ve looked at so many diagrams but I’m still not sure.
I did my best showing where each hose is going.

[HarryD]

I have no experience with MFI. Do an advanced search here. You want to look for threads about MFI and posted by Grady Clay. He wrote extensively about this issue.

Also, visit the Early 911S Registry BBS. Lots of expertise there as well.

[Winter911]

Originally Posted by HarryD

I have no experience with MFI. Do an advanced search here. You want to look for threads about MFI and posted by Grady Clay. He wrote extensively about this issue.

Also, visit the Early 911S Registry BBS. Lots of expertise there as well.

SHE RUNS!
As I was checking timing, I noticed that the distributor rotor cap was not seated correctly, probably from the first time I took it apart to do the “telegraph test”

Clicked it back in place and she started right up. Smoked a ton but then settled down.
I have to check fuel pressure because it dies when giving it a lot of throttle at once. It’s fine if you easy it up.

It’s also not smooth, so I’ll have to check the injectors and spark plugs to see what’s going on.

I can’t thank you all enough for all the help. This forum is fantastic and I encourage everyone to ask questions if you have any.

[HarryD]

GREAT NEWS.

There is a document in the tech section of the Pelican Parts web store called “Check, Measure, Adjust”. Factory manual for trouble shooting MFI systems.

One big take away, DO NOT TOUCH the the MFI pump until everything is spot on. This means a full tuneup (valve adjust, news plugs, points, cap, rotor, fuel filter, dwell set properly, and timing set properly). Check your fuel pressure.

I do not know if you can do do, but you also need to make sure your injectors are working properly. I may be worthwhile to reach out to Mark Jung in Oregon for some advice. I go not know if he will be helpful but he does s lot of MFI work.

[HarryD]

Just thinking here. Before you do anything too heroic, get some fuel injector cleaner additive for you fuel and run a tank or two of the stuff to see if it clears it up.

If you can, be sure to use non-ethanol fuel. Your car will thank you.

[HarryD]

Helpful links

https://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm

https://www.early911sregistry.org/forums/showthread.php?145167-MFI-troubleshooting-high-idle-pops-and-bucks-at-part-throttle

[Winter911]

Originally Posted by HarryD

Helpful links

https://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm

https://www.early911sregistry.org/forums/showthread.php?145167-MFI-troubleshooting-high-idle-pops-and-bucks-at-part-throttle

Thanks Harry, That’s a lot of useful information.
I’ll start going down the list this weekend.

Im hoping I can get it running smoothly soon to go out on a first drive.
In case any injector is bad, I’ll find some place to get them rebuilt (I just checked prices for new ones )
Same for the fuel pump.

[HarryD]

Originally Posted by Winter911

Thanks Harry, That’s a lot of useful information.
I’ll start going down the list this weekend.

Im hoping I can get it running smoothly soon to go out on a first drive.
In case any injector is bad, I’ll find some place to get them rebuilt (I just checked prices for new ones )
Same for the fuel pump.

Mark Jung. The links gave his info.

[Schulisco]

Great news that the engine is running now. If it stalls while cold running my experience is that it runs to rich on the mixture. I'm not in the MFis, only CIS, but I'm pretty sure that either the engine gets too much fuel or too little air...both leads to a too rich mixture with the effect that the engine stalls while pushing the accelerator too much. The effect that the engine runs while giving only a little throttle identifies the richer mixture - the slightly pushed throttle gives nearby a little extra fuel also a little bit more extra air that the engine remain running, but when push the accelerator a bit more, also more fuel comes with more, but in this case too few air. At the end the mixture is again way too rich and it stalls again...

Nevertheless - all parts of the injections system must be checked. This means follow exact the values given by Porsche that they're all in specification!

Good luck!

Thomas