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Quota 1000 Fuel Pump

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
Hey there!

New to the forum and new to the guzzi world.

Got myself a '91 Quota 1000. I bought it knowing that it had some running issues but I decided to bite the bullet anyway. This bike is to good looking and rare to be ignored.
First of all, is it normal for the fuel pump to run continuously? I guess it would stop once it got to a certain pressure.
I´ve balanced the throttle body and check the TPS... everything seems nice. However after riding a bit I have a very hard time to restart the engine. I will crank and crank but just won't fire up. If I let it cool down it will start again pretty easily.

Any thoughts on this guys?

Cheers from Portugal.
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,873
Location
Huntsville, AL
When you turn the key on, it should only run for a few seconds and stop. Once stops then try to start. Considering the age of the fuel pump, it may need replacement.
 

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
When you turn the key on, it should only run for a few seconds and stop. Once stops then try to start. Considering the age of the fuel pump, it may need replacement.
Thanks for your reply. I thought so as well. But since this is a very rudimentary EFI system I had my doubts.
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,873
Location
Huntsville, AL
Thanks for your reply. I thought so as well. But since this is a very rudimentary EFI system I had my doubts.

Duration of the fuel pump running is controlled by the ECU. There may be an issue with the programming. Or the fuel pump relay may be stuck closed making it run continuously. Let's hope it is the relay.
 

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
Thanks John. I'll check the relay. I wonder if the fuel pressure sensor is built in the pump or if it's external...
 

V700Steve

GT Reference
GT di Razza Pura
Joined
Dec 8, 2008
Messages
1,272
Location
Atlanta area, GA
There is no pressure sensor, it is timed by the ecu. There is a pressure regulator in the system to keep fuel at a steady 3bar in hoses to injectors. It is mechanical not electronic. It is in line on the 1000cc and on the return tap to tank on the 1100cc.
 
Last edited:

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
There is no pressure sensor, it is timed by the ecu. There is a pressure regulator in the system to keep fuel at a steady 3bar in hoses to injectors. It is mechanical not electronic. It is in line on the 1000cc and on the return tap to tank on the 1100cc.
Thanks Steve. I'm aware of that regulator. If memory serves me right, it has one fuel inlet supplied from the filter, one vacuum connection to the intake manifold, one outlet to the injectors and one outlet bypass to the tank.
But I'm missing something. If it is only timed, how can the that pressure (3bar) be maintained? I guess there would be a pressure drop sooner or later... Hummm

BTW... since my pump works continuously, there is a constant stream of fuel flowing back into the tank. This obviously can't be right.


Thanks for the feedback guys!
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,873
Location
Huntsville, AL
David,

The ECU runs the fuel pump for a few seconds to pressurize the system then shuts off. On a correctly functioning bike that is your indicator to start the engine. Once the engine is running, the ECU keeps the fuel pump running. Besides it being a stuck relay, someone may have bypassed that relay in the past to keep the pump running.
 

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
David,

The ECU runs the fuel pump for a few seconds to pressurize the system then shuts off. On a correctly functioning bike that is your indicator to start the engine. Once the engine is running, the ECU keeps the fuel pump running. Besides it being a stuck relay, someone may have bypassed that relay in the past to keep the pump running.
OK. That finally makes sense to me. Wouldn't be surprised if it had been bypassed... The bike has clear signs of being mistreated.
I'll keep you guys posted.
Cheers! Have a good one!
 

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
Hi!

So yesterday I finally had some time to get my hands on the Quota.
The relays seem to be working properly. Even interchanged the injection solenoid with the pump solenoid and nothing changed. I traced the pump wiring back to the ECU and everything seemed ok. The pump, on the other hand, seems to have been replaced. So, long story short, the pump runs continuously as soon as I flip the switch to RUN. So I guess it might be ECU related, as John Zibell pointed out.
But my pursuit for Gremlins didn't stop there. The horns work, but somehow someone bypassed the horn relay. I didn't think much of this so I plowed ahead.
I tested the engine head temperature NTC. It was ok.
Then I spotted the air sensor mounted underneath the left horn. It was clearly damaged... half of it was missing. How much can a non existing air temperature sensor affect the poor performance and the hard start when hot??
It's exactly the same model as the engine temperature sensor, so I'm going to order one right after I post this.

Cheers!
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,873
Location
Huntsville, AL
A damaged air temperature sensor will impact starting and running. It is part of the calculation for air density. It seems engine temperature has more effect on running, but the air temperature part of the equation is needed as well.
 

DavidN

Just got it firing!
Joined
May 14, 2019
Messages
7
Location
Portugal
So I finally replaced the air temperature sensor but the symptoms didn't change. I checked the valves and the intake had no clearance whatsoever. Tuned them but unfortunately the bike is still very difficult to restart when hot and stalls at full throttle. On a cold start the quota revs up nicely but as the engine starts to get warmer she will act up on me.
Considering going to a Guzzi dealer to see what they have to say.
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,873
Location
Huntsville, AL
Next possibility is the engine temperature sensor. Have you checked that yet? That sensor has more impact on a hot engine on controlling injector timing.
 

johnno

Cruisin' Guzzisti
GT Contributor
Joined
Nov 6, 2008
Messages
153
I have tested a few ECU on my 1100 sport I and it was always a faulty ECU once relay as been checked .
 

Moto-Uno

High Miler
Joined
Aug 7, 2016
Messages
579
Location
Burnaby,B.C
I s there a remote possibility that you may have a coil problem when it heats up ? Have a spare plug handy
and remove the ground electrode ( it simulates the spark energy required under compression) and simply
remove a plug lead , install test plug and crank engine to test for spark (test plug grounded of course ) Peter
 
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