Amphi Misses When Warm

LSolheim

Member
After 10 weeks of "no-clutch" the Achilles is finally strong enough, so we spent a great 1-1/2 hours on the lake!

I had removed the Pertronix module and replaced the original points & condensor (after replacing cap, rotor, wires, plugs, & coil), but she still misses to the point of dying when hot (NOT overheating). Seems to get worse with the headlights on, as if they drag down the electrical circuit. Runs great cold & warm.

Any suggestions, as I have run out of ideas?

Thanks,
--Larry
 

Ken Chambers

Platinum Subscriber
Hi Larry,

Have you monitored the voltage to the coil? Try connecting lengths of
wire to the coil and battery (fused). When the problem exhibits
itself hot wire the coil as a test to bypass a lot of connections.

Maybe it's a fuel problem. Do you have a spare carb?

Vacuum leak? I've seen the bottom flange on the carbs severely bent
due to over tightening on that thick insulating gasket. Vacuum
advance diaphragm? Can try plugging the vacuum line.

How about a stuck valve? Compression check but it may clear up when
it cools down.

Good luck. Please keep us informed.

Best,
Ken Chambers, CA
'64 Red


On Jul 18, 2009, at 2:28 PM, LSolheim wrote:


> After 10 weeks of "no-clutch" the Achilles is finally strong enough,
> so we spent a great 1-1/2 hours on the lake!
>
> I had removed the Pertronix module and replaced the original points
> & condensor (after replacing cap, rotor, wires, plugs, & coil), but
> she still misses to the point of dying when hot (NOT overheating).
> Seems to get worse with the headlights on, as if they drag down the
> electrical circuit. Runs great cold & warm.
>
> Any suggestions, as I have run out of ideas?
>
> Thanks,
> --Larry
 

Midwest Amphicar

Worlds Largest Amphicar Destination
Do not assume your new coil is a good coil. If you are using the small rotor . Go buy the good one from England. Later Dave the wave
 

LSolheim

Member
You know, Ken, last year I insulated the fuel lines and installed a backup
electric fuel pump just in case it was a fuel issue, but it had been so long
I forgot to flip the switch to see if the positive fuel pressure would solve
the problem. Bummer. Today I will reinstall the Pertronix module and
perhaps try another test drive. Thanks for stimulating the damaged brain
cells!



By monitoring "voltage to the coil" & hot wiring, I assume with those
directions you mean to run direct from the battery, rather than from the
ignition switch? That would take a lot of wire (and connections) out of the
circuit.



--Larry



From: Ken Chambers [mailto:]
Sent: Saturday, July 18, 2009 8:37 PM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-20490] Amphi Misses When Warm



Hi Larry,

Have you monitored the voltage to the coil? Try connecting lengths of
wire to the coil and battery (fused). When the problem exhibits
itself hot wire the coil as a test to bypass a lot of connections.

Maybe it's a fuel problem. Do you have a spare carb?

Vacuum leak? I've seen the bottom flange on the carbs severely bent
due to over tightening on that thick insulating gasket. Vacuum
advance diaphragm? Can try plugging the vacuum line.

How about a stuck valve? Compression check but it may clear up when
it cools down.

Good luck. Please keep us informed.

Best,
Ken Chambers, CA
'64 Red


On Jul 18, 2009, at 2:28 PM, LSolheim wrote:



Quote:



> After 10 weeks of "no-clutch" the Achilles is finally strong enough,
> so we spent a great 1-1/2 hours on the lake!
>
> I had removed the Pertronix module and replaced the original points
> & condensor (after replacing cap, rotor, wires, plugs, & coil), but
> she still misses to the point of dying when hot (NOT overheating).
> Seems to get worse with the headlights on, as if they drag down the
> electrical circuit. Runs great cold & warm.
>
> Any suggestions, as I have run out of ideas?
>
> Thanks,
> --Larry
 

LSolheim

Member
Thanks, Dave. The English rotor was one of the changes made last year,
although I had not personally seen the "rotor failure" problem. The coil is
Pertronix also. --Larry



From: Midwest Amphicar [mailto:]
Sent: Sunday, July 19, 2009 9:43 AM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-20490] Re: Amphi Misses When
Warm



Do not assume your new coil is a good coil. If you are using the small rotor
. Go buy the good one from England. Later Dave the wave
 

LSolheim

Member
I reinstalled the Pertronix, Ken, then checked coil voltage, which read
6.2v. I read 14.2v at the battery w/ the generator on-line.

Of course that coil voltage is AFTER the Pertronix igniter and I believe
there is also a ballast resistor under the hood (?) or maybe that was the
Jensen Healey.



We'll see what happens after a test drive.

--Larry



From: Ken Chambers [mailto:]
Sent: Saturday, July 18, 2009 8:37 PM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-20490] Amphi Misses When Warm



Hi Larry,

Have you monitored the voltage to the coil? Try connecting lengths of
wire to the coil and battery (fused). When the problem exhibits
itself hot wire the coil as a test to bypass a lot of connections.

Maybe it's a fuel problem. Do you have a spare carb?

Vacuum leak? I've seen the bottom flange on the carbs severely bent
due to over tightening on that thick insulating gasket. Vacuum
advance diaphragm? Can try plugging the vacuum line.

How about a stuck valve? Compression check but it may clear up when
it cools down.

Good luck. Please keep us informed.

Best,
Ken Chambers, CA
'64 Red


On Jul 18, 2009, at 2:28 PM, LSolheim wrote:



Quote:



> After 10 weeks of "no-clutch" the Achilles is finally strong enough,
> so we spent a great 1-1/2 hours on the lake!
>
> I had removed the Pertronix module and replaced the original points
> & condensor (after replacing cap, rotor, wires, plugs, & coil), but
> she still misses to the point of dying when hot (NOT overheating).
> Seems to get worse with the headlights on, as if they drag down the
> electrical circuit. Runs great cold & warm.
>
> Any suggestions, as I have run out of ideas?
>
> Thanks,
> --Larry
 
R

Ron Green

Guest
Larry,

Unsure what your problem might be but to do a quick check on your coil use a good ohmmeter (preferably digital) on the low voltage terminals. Four cylinder engines need 3 ohms minimum or greater (4 to 7 is a decent reading) while six or eight cylinder engines should read somewhere in the 2 to 5 ohm range (1 1/2 minimum. Amphi did not come with a ballast resistor. Check the coil / ohms cold and check it after it is warmed up or the engine dies. Coils can do strange things once they get hot and expand. Or if you have a coil you know is good swap it out for a test.

Good luck and I am glad to see you are getting around.

Ron Green
 

LSolheim

Member
Of course she has sat long enough that she runs OK, but I get 12.5v from the start switch wire (before igniter), so the 6v drop is through the Pertronix module. Whe she was warm, just before the problem the coil voltage had dropped to 5.8, but I wouldn't think that was significant.

Headlights on definately made the engine lug down and I did think to test the electric fuel pump - no difference. I also checked the tank flex vent tube & the 'crushed' pipe into the filler neck to insure nothing was clogged -- it wasn't.

The coil shows 3.8 ohm resistance. I'll get her hot and check both the switch voltage and the coil again.

Frustrating,
--Larry
 

LSolheim

Member
Further to all of this - the "missing" gets quite severe. Starts as a miss
and progresses to what seems like firing on three and then only 2 cylinders,
before quitting altogether. It REALLY needs to be figured out! --Larry



From: Ron Green [mailto:]
Sent: Sunday, July 19, 2009 12:45 PM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-20490] Re: Amphi Misses When
Warm



Larry,

Unsure what your problem might be but to do a quick check on your coil use a
good ohmmeter (preferably digital) on the low voltage terminals. Four
cylinder engines need 3 ohms minimum or greater (4 to 7 is a decent reading)
while six or eight cylinder engines should read somewhere in the 2 to 5 ohm
range (1 1/2 minimum. Amphi did not come with a ballast resistor. Check the
coil / ohms cold and check it after it is warmed up or the engine dies.
Coils can do strange things once they get hot and expand. Or if you have a
coil you know is good swap it out for a test.

Good luck and I am glad to see you are getting around.

Ron Green
 

Ed Price

Member
Always the same two cylinders? Try disconnecting a spark plug wire while
it's missing to determine which plug may not be firing. Then check the plug
for fouling or other bad signs. Also verify good grounding of the coil body
to the hull and good bonding of engine to hull.


Ed Price
El Cajon, CA USA
WB6WSN
61 Rust Guppy
1987 MB 420SEL






_____

From: LSolheim [mailto:]
Sent: Sunday, July 19, 2009 6:57 PM
To: edprice@cox.net
Subject: RE: [General Amphicar Discussion-t-20490] Re: Amphi Misses When
Warm


Further to all of this - the "missing" gets quite severe. Starts as a miss
and progresses to what seems like firing on three and then only 2 cylinders,
before quitting altogether. It REALLY needs to be figured out! --Larry
 
R

Ron Green

Guest
Any chance that when the fuel line gets warm it is sucking shut? Sometimes age weakens them. I have seen this a few times and it can drive you crazy trying to figure out what is wrong?
 

Ed Price

Member
_____

From: Ron Green [mailto:]
Sent: Monday, July 20, 2009 2:57 AM
To: edprice@cox.net
Subject: RE: [General Amphicar Discussion-t-20490] Re: Amphi Misses When
Warm

Any chance that when the fuel line gets warm it is sucking shut. I have seen
this a few times and it can drive you crazy trying to figure out what is
wrong?



Same thing can happen if the gas tank vent tube is constricted or blocked;
it takes a while to build a partial vacuum in the big gas tank, but once you
do, the fuel pump can't pull gas against it.


Ed Price
El Cajon, CA USA
WB6WSN
61 Rust Guppy
1987 MB 420SEL
 

Canadian four amphs

Amphicar Expert
You are decribing my Green Amphicar to a T in Fl. 2007,,
I insulated the fuel line back from carb to fuel pump and have never had a problem since!.
GORD
 

LSolheim

Member
Thanks, but did that when I added the b/u electric pump, Gord.



From: Canadian four amphs [mailto:]
Sent: Monday, July 20, 2009 6:52 AM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-20490] Re: Amphi Misses When
Warm



You are decribing my Green Amphicar to a T in Fl. 2007,,
I insulated the fuel line back from carb to fuel pump and have never had a
problem since!.
GORD
 

LSolheim

Member
Well, I think the plan will be to expose the connector where the ignition switch wire connects to the Pertronics wires. Then I'll make another test drive w/ an ohm meter and a small bottle of gasoline.

If the problem recurrs I can dribble gas into the carb and test the votlage coming from the ingnition switch.

If the added gas solves the problem I will certainly know it is not electrical. If the voltage from the ignition switch is low perhaps there is some corrosion in the LR connectors, although why a short wait would solve that, I do not know.

OTOH, perhaps my cleaning of the crush end of the tank inlet vent solved it all.

--Larry
 

LSolheim

Member
Standard location, Eric, thanks.



I used foam insulation topped by aluminum tape when I added the aux electric
fuel pump last year, just to rule out vapor locking.



I am beginning to lean toward the tank-venting issue. Yesterday it did not
happen during the first half of the test drive, until I filled the tank.
Although I did not see any residue when I checked the vent, today I opened
it a bit to insure it is clear. Will test drive again tomorrow after a day
of Achilles rest (a bit overdone yesterday).



--Larry



From: echassignet [mailto:]
Sent: Monday, July 20, 2009 2:48 PM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-20490] Re: Amphi Misses When
Warm



I think Gord is referring to vapor lock. Is your fuel line close to the
engine block?

Eric
67White
 
S

SplitPersonality

Guest
On the subject of vapor lock, as I was growing up and had my first car in
1950 ( ! ) I used to hear a lot about vapor lock, but eoither never
experienced it or didn't really know what it was. That all ended with a vehicle
in 1974 which drove me absolutely crazy. I finally resorted to an auxillary
electric fuel pump and whenever vapor lock threatened, I flicked on the
electric in line pump and the problem immediately ended.

In my Amphicar, I utilize an airtex low pressure electric p[ump full time (
I believe it is 2.5 - 4 psi or some such low pressure ). The mechanical
pump is simply disconnected, though still in place. The electric solenoid
on/off fuel switch is still in the circuit. I turn the ignition on which
activates the electric pump and wait 30-45 seconds to send the fuel back aft,
then hit the starter and it generally runs immediately. If the car has been
run in the last 24 hours or so, I don't have to wait at all, as the carb
bowl still has fuel in it and the engine tends to start immediately - and I
mean in a second or two. In my experience, if you have the pressure from
the electric pump pushing the fuel from the tank, vapor lock simply does not
occur. I have used the same system on numerous vehicles with 100% success.
Generally, it is best if the electric pump can be near the fuel tank to
push the fuel, rather than trying to suck is to the carburetor. However, in
my 1948 Ford, the ancient 6 volt electric pump is situated on the firewall
right by the engine. It is an in line pump and I simply switch the pump on
until I hear it put-put-put indicating that the pressure has filled the
carburetor bowl and then I switch it off, hit the starter button and voila, it
generally starts within 3 or 4 seconds with no prolonged grinding of the
starter to bring the fuel up to the carburetor.

All of this discussion, of course, is not applicable to fuel injected
engines in which the fuel flow is pressurized immediately. Anyway, this is my
personal experience and I swear by it. It allows me to prime engines
without endless or needless grinding of the starter to get the fuel up to the
engine from the fuel tank as well as to remedy any vapor lock problem which can
occur from the fuel line running to close to a manifold or hot engine
components or even just from idling waiting for a long traffic light.

Capt Splash with the 1967
"Split Personality" near Daytona


In a message dated 7/20/2009 5:49:30 P.M. Eastern Daylight Time,
writes:

I think Gord is referring to vapor lock. Is your fuel line close to the
engine block?

Eric
67White





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yExcfooterNO62)
 
S

SplitPersonality

Guest
Larry - Ron's suggestion to swap with a known good coil is very worthwhile.
With several cars over the years, I have had the darndest puzzling
symptoms and problems which ended up being a bad coil. Swapping parts can
sometimes be the quickest and easiest way to isolate the problem if you have a coil
available. It needn't be an Amphicar coil - just a good 12 volt coil and
the secondary connections appropriately connected.


Capt Splash near Daytona


In a message dated 7/19/2009 3:50:39 P.M. Eastern Daylight Time,
writes:

Larry,

Unsure what your problem might be but to do a quick check on your coil use
a good ohmmeter (preferably digital) on the low voltage terminals. Four
cylinder engines need 3 ohms minimum or greater (4 to 7 is a decent reading)
while six or eight cylinder engines should read somewhere in the 2 to 5 ohm
range (1 1/2 minimum. Amphi did not come with a ballast resistor. Check
the coil / ohms cold and check it after it is warmed up or the engine dies.
Coils can do strange things once they get hot and expand. Or if you have a
coil you know is good swap it out for a test.

Good luck and I am glad to see you are getting around.

Ron Green





**************A Good Credit Score is 700 or Above. See yours in just 2 easy
steps!
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JulystepsfooterNO62)
 

LSolheim

Member
I was quite confident that it was the “tank vent” solution, which I had opened up a bit thinking all would be well. WRONG. And when removing the cap there was no sudden “suckage”. So today’s test drive was a bit longer than planned as although I was able to duplicate the problem, I was unable to diagnose or solve the issue and I had to wait at several stops for 15 minutes at a pop until she would run OK to continue. I was not able to dribble into the carburetor slowly enough, so my gas “pour” just killed the motor when already missing (if it had run better I would have confirmed a fuel starvation problem).

Before the problem becomes mega-severe it seems that putting a load on the motor (trying to accelerate, turning on the lights or heater blower, etc) makes it worse. So perhaps we are talking fuel, but what would be heat or time related? A bad needle valve or float in the carb? I checked all of the hoses I could reach and none seemed to have the problem of collapsing or “sucking down”.

Turning on the electric fuel pump has no effect (which should push fuel through the system at it is just under the tank) and from its’ sound I can tell it is not running dry. I checked the oil and found no evidence that fuel was pumping into it, as if there were a bad diaphragm in the mechanical pump.

This is severely limits the hot weather boating!

--Larry
 
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