Can't Hear Fuel Pump Prime

[Guest percy]

205 has decided not to start today. When I turn the ignition the engine will turn over but not start. Normally I can hear the fuel pump prime but it's silent. before I ssplas out on a new fuel pump how do I test it's actually this at fault? Is there a relay that might be faulty?

Cheers.

[Jonmurgie 2]

Do a search for the Tachymetric realy as that may be the problem

[tom_m 0]

from a recent experience I'd say check your ignition before starting to take the fuel system apart.

 

mine cut out and would turn over but wouldn't run. I couldn't here the pump priming so like you assumed it was that. a continuity check showed current was flowing so we whipped the fuel pump out but it was fine. the fuel system wasn't priming because it was already primed!

 

went back to the beginning and checked for a spark and nada. turned out to be a loose wire on the ign amp.

 

of course ignore me if you've done this already!

[GLPoomobile 958]

Do a search for the Tachymetric realy as that may be the problem

 

Good luck with the search, as nobody can spell Tachometric relay correctly, as John has just illustrated

 

(I'm really leaving myself open to a good piss taking now, if I have spelled it wrong )

[Butler 0]

Take the seat up and put a multimeter across the fuel pump. If its 12v then get a pump, if not, try the relay.

[jackherer 543]

Good luck with the search, as nobody can spell Tachometric relay correctly, as John has just illustrated

 

(I'm really leaving myself open to a good piss taking now, if I have spelled it wrong )

 

I once thought that, but it is actually spelt tachymetric

 

tachymetric

 

Tachymetry \Ta*chym"e*try\, n. The science or use of the tachymeter. -- Ta`chy*met\"ric, a.

 

tachy-

pref. Rapid; accelerated: tachymeter. [Greek takhu-, from takhus, swift.]

 

tachy-

pref.

 

Rapid; accelerated: tachycardia.

[steve@cornwall 100]

Take the seat up and put a multimeter across the fuel pump. If its 12v then get a pump, if not, try the relay.

 

You can take off the fuel pipe from the rail (carefull-pressurised fuel ) , put the end into a container and crank the car- 5 mins and you'll know for sure if the pump/relay etc. is working!

[Ahl 4]

The tachymetric relay also controls the injectors though, so that method doesn't guarantee that it isn't gubbed, only the fuel pump.

 

However, if you can't hear it prime even when left for a bit, it probably is the relay. Its a lot more common than fuel pumps going on the blink.

[GLPoomobile 958]

I once thought that, but it is actually spelt tachymetric

 

 

Awww, ball sack

 

Sorry John I must stop being so facetious!

[jackherer 543]

Sorry John I must stop being so facetious!

 

me too!

[pug_ham 242 3 Cars]

Have you checked for a spark?

 

I've found they don't always prime, the one on my old 309 never did (had the car 10 years) but it never failed to start.

 

On various 205's I've had they sometimes do & sometimes don't, never the same twice in a row.

 

Graham.

[Guest percy]

Thanks for the various theories pug community, first thing to do would be check the relay so i'll do a search unless someone would be happy just to tell me where it's located - glove box? Of course I have no idea how i should test it, perhaps just hit it with a lump hammer. I'll have a look at ignition too? It's strange but you get used to the way a car sounds on start-up, it's sat in the garage and is normally started once a month and every time i've heard the pump prime, so I guess the fuel system must loose pressure over that period. Some good advice here guys.

[pug_ham 242 3 Cars]

On a 1988 205 the tachymetric relay could be inside the car by the ecu under the drivers side dash in the hole in front of your right knee if you have the later dash with round controls for the heater but if you have the vertical sliders it should be in the engine bay next to the battery tray in a black box.

Of course I have no idea how i should test it, perhaps just hit it with a lump hammer

Hitting it with a lump hammer will result in a smashed relay & you will need a new one then.

 

Best way to test is by fitting a known good one & see if it fixes it.

 

Graham.

[Rob_the_Sparky 9]

Although it might just be worth checking you have a spark first as it is the easiest thing to check and a quite likely cause of a non-starting car.

[Guest percy]

Found the relay Graham under the dash next to the ECU - there is only one there so I assume it's this, I removed and replaced just incase of a dry joint but no different. Is there a fuel pump relay or fuse that controls the pump in the fuse box (glove compartment)? Would an immobiliser be wired into the pump or are they normally starter motor/ignition. I'll have a check for a Spark 2mrw Rob.

Thanks.

[mi16nut 0]

I tested mine by running a temporary live feed directly to the pump. If it starts, it's more likely to be the tachymetric relay, or less likely to be a break in the wire. Could be the injector relay?

 

The lack of a spark will stop the fuel flowing, so it's difficult to identify what's the cause of the problem. Mine sat for 2 weeks last year (got fed up & left it!). Turned out to be a broken wire going to the injector relay. As with anything like this, it's a patient process of ellimination.

 

Mark.

[Ahl 4]

Found the relay Graham under the dash next to the ECU - there is only one there so I assume it's this, I removed and replaced just incase of a dry joint but no different. Is there a fuel pump relay or fuse that controls the pump in the fuse box (glove compartment)? Would an immobiliser be wired into the pump or are they normally starter motor/ignition. I'll have a check for a Spark 2mrw Rob.

Thanks.

Was it a big black relay? That would be the tachymetric one.

Be aware that lots of relays will fit in the socket, but virtually none of them will work - the tachymetric one is quite specialised.

 

If you do a search you should find the wire numbers for the live, fuel pump and injectors on the tachymetric relay socket. You can try bridging these with small bits of wire - this will make the fuel pump run continuously, but if it starts you know the relay was knackered.

[Rob_the_Sparky 9]

The lack of a spark will stop the fuel flowing, so it's difficult to identify what's the cause of the problem.

 

Mark.

 

Not entirely true, some things that stop the spark will have this effect but not all.

[pug_ham 242 3 Cars]

Found the relay Graham under the dash next to the ECU - there is only one there so I assume it's this, I removed and replaced just incase of a dry joint but no different. Is there a fuel pump relay or fuse that controls the pump in the fuse box (glove compartment)? Would an immobiliser be wired into the pump or are they normally starter motor/ignition. I'll have a check for a Spark 2mrw Rob.

Thanks.

There is only one relay next to the ecu, like Ahl says its black & is the tachymetric relay which controls the fuel pump & injectors.

 

The fuse is #14, should be a blue 15amp fuse thats the inner most on the fusebox.(see attached picture)

 

Graham.

[Guest percy]

That's a beautiful sound - she's running again. Having checked all the fuses and associated relays it seemed sensible to check for a Spark. Took a plug out turned her over and no spark, could smell fuel in the cylinder though. Took the distributor off, cleaned it up but no spark, checked connections to coil and earth - all o.k. I then noticed a brown block connector just in front and below the thermostat housind which fed into two sensors on the back of the engine block. After spraying some WD40 on the connetion (corroded) she started first turn of the key!!! Anyone know what the sensors do?

Graham - you were right about he fuel pump not always priming - didn't here it prime at all so must stay pressurised for some time. Thanks for all the advice, spured me on to get to the bottom of it. Now going out for a long awaited blast.

Edited August 18, 2006 by percy

[jonneh87 0]

im going to ask a silly question here because im having similar problems with my pump,

what does the tachymetric relay actually do??

does it alter the voltage going to the pump acording to the engine speed??

 

i ask because i have put a saxo vts engine and loom into my 205 running a 205 pump, the feed for the saxo pump is 12v, when i turn the ignition on i can hear the pump make a small clunk but its definatly not spinning/pumping.it does this with both the (untested) pumps i own but it works fine with a known good pump form my mates gti??

any sugestions welcomed! this is the last thing to sort before it drives.

[B1ack_Mi16 67]

im going to ask a silly question here because im having similar problems with my pump,

what does the tachymetric relay actually do??

does it alter the voltage going to the pump acording to the engine speed??

 

i ask because i have put a saxo vts engine and loom into my 205 running a 205 pump, the feed for the saxo pump is 12v, when i turn the ignition on i can hear the pump make a small clunk but its definatly not spinning/pumping.it does this with both the (untested) pumps i own but it works fine with a known good pump form my mates gti??

any sugestions welcomed! this is the last thing to sort before it drives.

 

The relay is just supposed to provide a constant +12v feed to the fuelpump.

Maybe some of the realys have the function that they'll give +12v for some few seconds (priming) after turning ignition on (I've heard about it, but never seen it myself).

 

The voltage to the pump is always 12v, the fuel pressure is kept constant by the fuel pressure regulator.

[jonneh87 0]

cheers, i must have just got 2 faulty pumps then. ah well sorted now.

j