Silvertop loosing power while driving..

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BlueAngel
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Silvertop loosing power while driving..

Postby BlueAngel » Thu Jan 13, 2022 11:02 am

I need help from the Silvertop 4AG experts in this forum. this is my situation.
I replaced the sender unit to correct the inaccurate reading in the instrument cluster. few days after the replacement, the FX now lose power while driving, the car start shaking and dies. this is very dangerous because it happened several time in the hwy and I was about to get rear ended.
when that happened, I have to try several times to crank it, at times it cranks but with a very low RPMs making a noise as if it getting limited fuel.
I would like to replace the fuel pump, the fuel filter, the distributor cap, and spark plugs cables, but I cannot find part numbers.
I already got the spark plugs and the distributor rotor.

Do you guys have any idea what could be causing this issue? the engine it's installed in a AE82 Corolla FX.
Please help.
thank you all in advance.

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jondee86
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Re: Silvertop loosing power while driving..

Postby jondee86 » Sat Jan 15, 2022 3:31 pm

It certainly sounds like you have a fuel supply problem. So to clarify...
1. Before the problem the engine ran fine... normal power, no hesitation ?
2. Was there a gradual loss of power or did it just lose power completely ?
3. When it started again and you were driving, did the engine run normally
up to the point when the problem came back ?
4. Does the engine start normally from cold now ?
5. What was the outside temperature when the problem occurred ?
6. Have you checked the colour of your sparkplugs ?
7. Can you get the fuel pump out without dropping the tank ?
8. What was the sensor you changed ?

Cheers... jondee86
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persists in trying to adapt the world to himself. Therefore, all progress
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BlueAngel
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Re: Silvertop loosing power while driving..

Postby BlueAngel » Sun Jan 16, 2022 11:28 am

Thank you for your response Jondee86,
to response to your questions:
1. Before the problem the engine ran fine... normal power, no hesitation ?
yes, the engine was running normally, before this problem. it only started a week ago

2. Was there a gradual loss of power or did it just lose power completely ? while driving, it looses power, the dies.
3. When it started again and you were driving, did the engine run normally
up to the point when the problem came back ? When I get to crank again (sometimes takes a while) it runs fine, until it start puffing again and dies.
4. Does the engine start normally from cold now ? the engine starts normally from cold, sometimes it takes couple of tries but it cranks.
5. What was the outside temperature when the problem occurred ? the problem started about a week ago and the first time it did it, temperature was about 60-65 degrees.
6. Have you checked the colour of your sparkplugs ? the spark plugs were dark, seem normal, but the had just been replaced.
7. Can you get the fuel pump out without dropping the tank ? I think so, I believe the shop that performed the swap about 8 years ago, had to install an aftermarket fuel pump as the carburetor engine that was removed from the FX had a manual pump. I would have to call them and ask them, or try to get under the car and check if I can see it. the shop is in florida, I live in North Carolina now.
8. What was the sensor you changed ? no sensor was replaced, I replaced the Fuel Sender Unit from inside the gas tank. accesible by removing the rear seat.
I also, waiting for a Fuel Pressure Tester because I was advise by a technician to check for the fuel pressure while driving it to see if the fuel pump is dying or losing pressure while driving.
I wish I could upload a video of what it does when it dies. but I don't see any options to upload one.
base on the info provided, what do you think could be causing this problem?

thank you in advance Jondee86

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jondee86
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Re: Silvertop loosing power while driving..

Postby jondee86 » Sun Jan 16, 2022 1:00 pm

It is not possible to upload a video (or pics) directly to this site. You need to upload
to a hosting service such as Youtube (or Imgur for pics), and then post the link here.

From the information I would say everything points to a fuel supply problem. Either
your fuel pump is on the way out or you have a blocked filter. If you have an in-tank
pump there should be a sock filter on the pickup to stop debris from the bottom of the
tank getting into the pump. If you have a lot of rust inside the tank it can clog the filter
to the point of starving the pump. You should be able to inspect the inside of the tank
thru opening for the fuel level sensor without dropping the tank.

If you have an external (in-line) pump there should be a filter installed between the
pump and the fuel outlet from the tank. This may be clogged. With an in-tank pump
there should be a EFI filter installed in the fuel supply line, usually in the engine bay.
These usually cannot be opened for cleaning and need to be replaced if clogged.

Your engine needs around 35psi in the fuel rail for the injectors. A failing pump or a
clogged filter can reduce fuel pressure to the point where the air/fuel ratio becomes
too lean to support combustion, and the engine will die. Testing the fuel pressure with
a gauge connected to the fuel rail and the engine running is a good idea. The fuel
pressure regulator on the engine is vacuum compensated, so there will be some small
change in pressure as you rev the engine. But if you see the pressure drop by 10 or
15psi either the pump is bad or there is an obstruction to flow.

A simple test that you can do without the engine running is to disconnect the fuel return
hose close to the engine and using a spare piece of hose, direct the fuel into a clear glass
bottle. Have someone turn the ignition ON briefly without cranking, and observe the flow
of fuel into the bottle. You may need to use a jumper wire to force the fuel pump to run
if it does not prime with ignition ON. There should be a strong jet of fuel. If the flow is
weak like it was just draining out by gravity, that indicates a lack of pressure in the rail.

So I would suggest the following steps...
1. Inspect the inside of the tank to see if it is clean or has a layer of sludge at the bottom.
2. Locate, clean or replace all or any fuel filters (look for signs of rust particles).
3. Inspect fuel lines for damage, kinks, flattening etc.
4. Test for pressure.
4. Test for flow.

There are a few other less likely things that can cause fuel starvation, so better to check
and eliminate the obvious before chasing ghosts :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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BlueAngel
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Re: Silvertop loosing power while driving..

Postby BlueAngel » Sun Jan 16, 2022 1:20 pm

Thank you Jondee86,
You advise has been a great help.

I will update once I perform all the test, (waiting for the snow and ice from the storm to melt first).
I will end up replacing the fuel tank if necessary.

Have a great day!
Alberto Arias

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Re: Silvertop loosing power while driving..

Postby allencr » Thu Jan 20, 2022 9:32 am

BlueAngel wrote:... I have to try several times to crank it, at times it cranks but with a very low RPMs making a noise as if it getting limited fuel.


Can it wind out 2nd & 3rd gear, 5-6K rpm without any problem, before the problem starts?
If so, there is no fuel problem. There may be a not really a fuel problem, only so far as the pump isn't getting enough current because something is getting hot - relay -switch -connection/s.

'cranks but with a very low RPMs' and 'making a noise as if' statements confuse & scare me!
Slow is an elec. problem and I'll have to assume noise is just intermittent firing & trying to run.
///////
I try to never answer the OP's guess/s about what's wrong, only about the symptoms & suggest how to show their guess is wrong. The OP guess is usually a useless wild goose chase way way more often then not.    

jondee86 loves to run with their guess/s and I love him for it and for his writing skill & knowledge & helpfulness and would absolutely hate to dissuade him one bit, just because I'm an asshole & afraid he'll burnout.
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Re: Silvertop loosing power while driving..

Postby jondee86 » Thu Jan 20, 2022 12:33 pm

Love your work allencr... don't ever change :D I know there can be several
different reasons for most intermittent running problems, but I figure checking
and eliminating fuel supply as a cause is as good a place to start as any. Fuel is
something that can be seen and measured, so more easily understood by anyone
doing their own troubleshooting.

Electrical problems are a lot harder to track down as they "disappear" once the
car has sat for for a few minutes. After that everything is business as usual for
a while, until they appear again at the next awkward moment. For anyone
without a full understanding of how the electrical systems on a car work, it often
becomes a case of shooting in the dark and replacing components unnecessarily.

You obviously have a vast knowledge gained from years of experience, and your
comments are always incisive, terse and to the point !!!

Hope you are doing OK in this crazy world. Stay safe.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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BlueAngel
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Re: Silvertop loosing power while driving..

Postby BlueAngel » Sat Jan 22, 2022 5:35 am

[quote="jondee86"]It is not possible to upload a video (or pics) directly to this site. You need to upload
to a hosting service such as Youtube (or Imgur for pics), and then post the link here.

Perhaps this can help. This is what it’s doing.
By the way, when that light under the dash it’s on, the car has no power, as you can see in the video.
Videos are part 1and 2

https://youtube.com/shorts/LnI6undAXsk?feature=share
https://youtube.com/shorts/aEqUoot6X9Q?feature=share

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Re: Silvertop loosing power while driving..

Postby jondee86 » Sat Jan 22, 2022 1:14 pm

Sounds to me like it running extremely lean... barely enough fuel to support
combustion. You definitely want to try the fuel into a bottle test while it is in
that condition.

An engine needs very little fuel to idle, but once you open the throttle and put
a bit of load on the engine the required fuel increases. So if you start trying to
raise the revs and the engine refuses or dies, it is likely a fuel problem.

Does the engine sometimes recover from that not wanting to run condition and
operate as usual (with normal power) ? Like you can drive for ten minutes
without a problem and then it just loses power and you have to pull over ? And
when you disengage the clutch (or knock it into neutral) the engine dies ?

The light under the dash could be connected to the CEL output on the ECU.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
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Re: Silvertop loosing power while driving..

Postby BlueAngel » Sat Jan 22, 2022 2:26 pm

jondee86 wrote:Sounds to me like it running extremely lean... barely enough fuel to support
combustion. You definitely want to try the fuel into a bottle test while it is in
that condition.

An engine needs very little fuel to idle, but once you open the throttle and put
a bit of load on the engine the required fuel increases. So if you start trying to
raise the revs and the engine refuses or dies, it is likely a fuel problem.

Does the engine sometimes recover from that not wanting to run condition and
operate as usual (with normal power) ? Like you can drive for ten minutes
without a problem and then it just loses power and you have to pull over ? And
when you disengage the clutch (or knock it into neutral) the engine dies ?

The light under the dash could be connected to the CEL output on the ECU.

Cheers... jondee86


Yes, the engine sometimes recover from the issue and I can keep driving, the other few times that have done it, I have to pull to the side of the road and try to start it again.
When it loses power, if dies if I let the clutch go, or if I put it in neutral.

Today I performed a fuel pressure test, the car started with no hesitation and ran for a little while, but I could stay outside to wait till it dies because it was too cold. about 18 degrees.
I will do it again and probably take it for a drive and while the gage is still connected to monitor what happens when it start doing that.
below are two videos, one testing the fuel pressure coming into the engine, the other one is on the return line.
the return shows about 15 PSI and I accelerate it goes down to 10PSI.

please let me know what you think. I am about to just replace the fuel pump and the fuel filter.
thanks

https://youtu.be/tWaxBV-_pI8 (testing the fuel going to engine)
https://youtu.be/xgEEmymGQ0s (test on the return line)

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Re: Silvertop loosing power while driving..

Postby jondee86 » Sat Jan 22, 2022 3:24 pm

Those pressures are indicate a normal healthy fuel pressure. The rail pressure increases
as you blip the throttle which is how it should be, and the return pressure goes down
because more fuel is going into the engine and less back to the tank.

Go ahead and replace the fuel pump and filter. I'd be surprised if that does not make the
problem disappear. There is a small possibility that a bad power or ground connection on
the pump could be part of the problem, so make sure that you check and clean (if necessary)
all the electrical connections while you are in there.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Re: Silvertop loosing power while driving..

Postby BlueAngel » Fri Feb 11, 2022 7:50 am

Just wanted to give you a quick update. After testing and confirming fuel pressure. I relocated the ground point. Then based on an advise from an old school technician at one of the Toyota dealer that I service, he mentioned the problem could be on the Air Flow Meter as the unit controls the fuel and air mixture to the engine. I proceeded to take the Air Flow Sensor apart and performed a thorough cleaning. The FX have been working and running very well since that.
So, I will be confident to say that the problem seems to be corrected.
Luckily, I found a person in charge bay selling the original Air Flow Sensor, the distributor w/ distributor cap, rotor and Cables, as well as the igniter, relay and coil pack, all form a silvertop engine. I purchased all items from him and will be replacing everything over this weekend.
But the FX has been running excellent since the cleaning of the Air Flow Meter.
Thank you all for the advises and help.
Have a great weekend!
Alberto Arias

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Re: Silvertop loosing power while driving..

Postby jondee86 » Fri Feb 11, 2022 2:17 pm

Ha !!! I am so used to working with MAP sensored engines I forgot that you might have an AFM... my bad :(
But good that you got it fixed. Your tech was right... those swing flap AFM's have a switch that has to operate
when the engine cranks and starts to suck in some air. If the flap gets sticky and doesn't move far enough
to operate the switch, the engine won't run. Also there are few other things that can go wrong with the AFM
so good to have spare in the shed.

Thanks for the update.... cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.