Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Vapor Lock?


Recommended Posts

Hi folks,

I have a 95 Echelon, and last summer I was having real problems starting it after it sat hot for a more than like twenty minutes. It starts right up when it's cold or even right after it's been running. Any ideas?

Link to comment

I suspect it's an electric fuel pump, but I haven't looked. It's a Mercruiser EFI engine.

Yes, it cranks like a champ. As I recall it would start for a second but then cut out immediately. Then it just dry cranks. I'd let it sit for a while and then try again. After twenty or thirty minutes it would start to sputter start and then eventually it would start. It would run perfect after that, perfect at cruise, idle, and acceleration.

Link to comment

If you pull the neutral knob and give it full throttle (I can only do that in the reverse direction) will it start? Does it smoke a bit when you do get it restarted? Then, my friend, you most likely have a bad engine temperature sensor. Mine acted exactly like you are describing last year and it turned out to be the temperature sensor. $25 and 10 minutes and you are back in business.

Link to comment
If you pull the neutral knob and give it full throttle (I can only do that in the reverse direction) will it start? Does it smoke a bit when you do get it restarted? Then, my friend, you most likely have a bad engine temperature sensor. Mine acted exactly like you are describing last year and it turned out to be the temperature sensor. $25 and 10 minutes and you are back in business.

just out of curiosity was your temp guage not working correctly? how did you figure out it was the temp sending unit ??

Link to comment
If you pull the neutral knob and give it full throttle (I can only do that in the reverse direction) will it start? Does it smoke a bit when you do get it restarted? Then, my friend, you most likely have a bad engine temperature sensor. Mine acted exactly like you are describing last year and it turned out to be the temperature sensor. $25 and 10 minutes and you are back in business.

I don't recall if I tried giving it full throttle, but I bet I did. It flat wouldn't start, not even a hint, not for 20-30 minutes. I also don't recall it smoking either. It would just start to hit a little more every time I tried to start it. I'd wait a few more minutes, and try again. Every time a little more until it started.

I'm going to pull it out this weekend and see what it does. I was just hoping to get some ideas before I started with it.

Link to comment

Do you have fuel injection or Throttle Body? Does a 95' have that much control to the PCM that the temp. sensor would let this happen?

Link to comment
If you pull the neutral knob and give it full throttle (I can only do that in the reverse direction) will it start? Does it smoke a bit when you do get it restarted? Then, my friend, you most likely have a bad engine temperature sensor. Mine acted exactly like you are describing last year and it turned out to be the temperature sensor. $25 and 10 minutes and you are back in business.

just out of curiosity was your temp guage not working correctly? how did you figure out it was the temp sending unit ??

There are two temp senders. one for the computer operating at 5 volts, and one for the gauge operating at 12 volts. They are not connected electrically in any way. The one for the computer has two wires connected to it. If you unplug the two wire sensor and measure the resistance of it, you should read about 3000 ohms at cold engine and about 500 at normal engine operating temp.

Link to comment
If you pull the neutral knob and give it full throttle (I can only do that in the reverse direction) will it start? Does it smoke a bit when you do get it restarted? Then, my friend, you most likely have a bad engine temperature sensor. Mine acted exactly like you are describing last year and it turned out to be the temperature sensor. $25 and 10 minutes and you are back in business.

just out of curiosity was your temp guage not working correctly? how did you figure out it was the temp sending unit ??

There are two temp senders. one for the computer operating at 5 volts, and one for the gauge operating at 12 volts. They are not connected electrically in any way. The one for the computer has two wires connected to it. If you unplug the two wire sensor and measure the resistance of it, you should read about 3000 ohms at cold engine and about 500 at normal engine operating temp.

You must work on these Thumbup.gif

Link to comment
If you pull the neutral knob and give it full throttle (I can only do that in the reverse direction) will it start? Does it smoke a bit when you do get it restarted? Then, my friend, you most likely have a bad engine temperature sensor. Mine acted exactly like you are describing last year and it turned out to be the temperature sensor. $25 and 10 minutes and you are back in business.

just out of curiosity was your temp guage not working correctly? how did you figure out it was the temp sending unit ??

Temp guage was and is just fine. I tried to diagnose my rpblem on this site and you guys came close but I ended up having to take it to my dealer who diagnosed the bad sensor.

Link to comment
Do you have fuel injection or Throttle Body? Does a 95' have that much control to the PCM that the temp. sensor would let this happen?

It's throttle body, and I have no idea why this would be happening. I'm just hoping there might be something simple I could check myself. Taking it to the shop will be a royal pain in the butt.

Link to comment

Sure sounds like vapor lock...try propping up the engine box slightly and running the blower while it sits for those 20 minute spans. Just curious, do you also have the insulated motorbox...I think that adds to the problem.

Link to comment

Or even open the motor box completely. It is definetly a symptom that sound like vapor lock, but why all of a sudden after 17 years? If you remove your flame arrester, you will be able to see if your injectors are spraying when cranking the engine. Just don't put your face directly over the throttle body in case of a backfire. Experience has taught me that electrical connectors and connections tend to loosen up with heat and age. Check the connectors on your distributor and coil. Also on your ECM relay(if Merc. uses one) which sends the run power to your ECM. Good luck.

Edited by electricjohn
Link to comment
  • 2 weeks later...

Well, I finally took it out, cleaned it up, charged up the battery, put some fresh gas in it, and now it won't start at all. I can see that the fuel injectors aren't spraying any fuel at all. Any suggestions? It has been garaged for about a year without any use.

Link to comment
I would start with the fuel pump fuse, fuel filter and fuel pump...

The electric fuel pump is working. Well, let's say it's definitely turning on. I don't know about the mechanical one. I'm going to replace the fuel filter today.

Edited by brettc
Link to comment

I replaced the fuel filter, and it started right up. It's running like a champ. I let it run for quite a while at 160 degrees. I shut it off for about a half hour, and it had no hesitation starting right up again. Even though it was sitting in the shade, I can't imagine this is a whole lot different than the last time I ran it. I'll probably take it out next weekend, and we'll see.

I'm thinking this vapor lock issue was just bad gas. I may have bought that gas early in the season, and I have a service bulletin about vapor lock from using "winter grade" gas.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...